Pith. sign in

REVIEW 4 major objections 5 minor 5 cited by

CAPA: Continuous-Aperture Arrays for Revolutionizing 6G Wireless Communications

T0 review · 4 major / 5 minor · reviewed 2026-08-12 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read Continuous-aperture arrays can outperform discrete antenna arrays in 6G wireless links, the paper argues, by treating the whole surface as one controllable current distribution.

desk verdict A useful CAPA survey that overstates its case: the quantitative gains come from companion papers and only hold against undersampled SPDAs, not the lambda/2 baselines the paper itself concedes are comparable. read the letter →

arxiv 2412.00894 v2 pith:TNLGKLSD submitted 2024-12-01 eess.SP

Yuanwei Liu , Chongjun Ouyang , Zhaolin Wang , Jiaqi Xu , Xidong Mu , Zhiguo Ding This is my paper · ORCID
classification eess.SP
keywords continuous-aperturearrayCAPA6Gwirelessbeamformingintegraloperatoreffectivedegreesoffreedomdiversity-multiplexingtradeoffmetasurfaceantenna
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

CAPA is a proposal to treat the antenna aperture as an electrically large surface with a continuously controllable current distribution instead of a set of discrete radiating elements. The paper argues that this continuous formulation is not just a modeling convenience: it turns beamforming into a functional optimization problem that can be solved near-optimally with low computational complexity, and it exposes a finite number of effective spatial degrees of freedom that discrete arrays can approach only with dense half-wavelength spacing. Three hardware routes are reviewed (electronic metasurface leaky-wave antennas, optically driven tightly coupled arrays, and acoustically driven grating arrays), and three beamforming strategies are compared: discretization, calculus of variations, and a subspace method. The reported performance analysis indicates that CAPAs achieve higher single-user and multiuser capacity regions than discrete arrays and better diversity-multiplexing tradeoffs, with gains that grow with aperture size. The main caveat is that the numerical comparisons assume an ideal aperture with no mutual coupling.

What carries the argument

The load-bearing object is the radiation (spatial response) operator, the integral operator that maps the continuous current distribution on the aperture to the received field. This operator is compact because its kernel is analytic and square-integrable, so it admits a Hilbert-Schmidt decomposition analogous to the singular value decomposition of a matrix; the squared singular values plateau then fall off, defining the number of effective spatial degrees of freedom. Band-limitedness in the wavenumber domain justifies Nyquist sampling and connects the operator to random-matrix analysis of fading channels. The beamforming designs ride on this operator: calculus of variations finds optimal currents directly as functions, while the subspace method expresses the optimal current as a finite combination of user spatial responses, reducing functional optimization to low-dimensional discrete optimization.

What would settle it

Measure or simulate the full-wave radiation operator of a real CAPA prototype, including mutual coupling and discretized tuning elements, and compute its singular-value spectrum; if the spectrum does not show a sharp plateau-then-decay shape, or if the capacity computed from the measured operator falls back to the discrete-array baseline at comparable aperture size, the ideal-continuous-aperture premise is falsified. A simpler test is to build two apertures of the same size, one discrete with half-wavelength spacing and one continuous or metasurface-based, and compare their measured ergodic capacity in the same scattering environment.

Watch

Extended reading notes

Core claim

The central claim is that a continuous-aperture array yields superior wireless transmission capabilities to a conventional spatially discrete array, and that the integral-based signal model is the reason: the spatial response of a CAPA is a compact integral operator whose Hilbert-Schmidt decomposition exposes a finite number of effective degrees of freedom. Because the operator's kernel is analytic and square-integrable, it is 'almost finite-dimensional'—its singular values stay flat and then decay sharply—so the channel can be captured by a small set of basis functions rather than a high-dimensional matrix. The paper reports that calculus-of-variations and subspace beamformers reach near-optimal spectral efficiency at low complexity, and that CAPAs enlarge capacity regions in single-user, multiple-access, and broadcast channels, while also improving the diversity-multiplexing tradeoff relative to discrete arrays, especially when discrete element spacing exceeds half a wavelength.

Load-bearing premise

The numerical performance gains assume an ideal CAPA whose current can be controlled continuously with no electromagnetic mutual coupling, and a radiation operator that is analytic, square-integrable, and band-limited in the wavenumber domain; if real materials, finite control resolution, or coupling break these properties, the predicted gains over discrete arrays may shrink or vanish.

Editorial extensions

If this is right

  • With the calculus-of-variations and subspace designs, CAPA beamforming can reach near-optimal spectral efficiency without solving high-dimensional matrix optimizations.
  • For a fixed aperture size, CAPAs achieve larger single-user, multiple-access, and broadcast capacity regions than discrete arrays, and the gap widens as the aperture grows.
  • In fading channels, CAPAs realize larger diversity and multiplexing gains than arrays with antenna spacing above half a wavelength, approaching the aperture's effective-degree-of-freedom limit.
  • Wavenumber-domain discretization lets existing discrete optimization toolboxes be reused for CAPA design, at the cost of a slight performance loss.
  • The three hardware routes trade form factor, cost, and frequency selectivity, with optically driven CAPAs best suited to wideband multi-carrier operation.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the compact-operator view transfers, the same continuous-aperture formalism should predict analogous effective-degree-of-freedom limits for optical phased arrays and acoustic transducers, where apertures are naturally continuous; this cross-domain prediction is not pursued in the paper.
  • The paper's own admission that MAC-BC duality for CAPA broadcast channels relies on heuristics and holds only for two users suggests a concrete open problem: prove that the capacity-achieving dirty-paper beamformer lies in the user signal subspace, which would generalize the multiuser capacity region.
  • A full-wave simulation campaign that includes mutual coupling could quantify how much of the CAPA gain survives hardware non-idealities; one plausible outcome is that gains persist at large aperture sizes but shift to lower frequencies where effective element spacing is denser.
  • Because the effective degrees of freedom scale with aperture and inversely with wavelength, a practical regime where CAPAs matter most is millimeter-wave and sub-THz small-cell links, where aperture dimensions in wavelengths are large and discrete arrays become impractically dense.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 5 minor

Summary. This paper presents continuous-aperture arrays (CAPAs) as a candidate architecture for 6G wireless communications. It reviews a commercial Kymeta prototype and three hardware implementations (electrically, optically, and acoustically driven), introduces three beamforming design frameworks (discretization, calculus of variations, and subspace methods), and reports numerical comparisons of spectral efficiency, channel capacity, capacity region, and diversity-multiplexing tradeoff between CAPAs and conventional spatially discrete arrays (SPDAs) under an ideal continuous-current model. The paper concludes with open problems in channel estimation, wideband transmission, and tri-polarized beamforming.

Significance. The survey of hardware implementations and the integral-operator formulation are useful and provide a coherent alternative to matrix-based MIMO analysis. If the claimed performance gains survive a fair comparison against λ/2-spaced SPDAs and under non-ideal hardware effects, the paper identifies a potentially important direction for extremely large aperture arrays. However, the central quantitative claims are not self-contained, and the paper's own Section IV-B substantially qualifies the headline superiority claim. The significance is therefore conditional on revisions that supply verifiable baselines and clearly separate ideal-model results from practical expectations.

major comments (4)
  1. [Section I.B] The blanket statement that "CAPAs yield superior wireless transmission capabilities to SPDAs" is not supported by the paper's own analysis. Section IV-B concedes that "for SPDAs with half-wavelength antenna spacing or less, the achievable DMT closely approaches that of CAPAs" and that a clear CAPA advantage occurs only for spacings larger than half a wavelength. Since λ/2-spaced SPDAs are the standard practical baseline, the abstract and introduction must either qualify the superiority claim or demonstrate gains against a λ/2-spaced SPDA baseline.
  2. [Figures 2(c), 3(a)-(c), 4(a)-(b)] All simulation parameters are deferred to companion papers ("Other simulation parameters can be found in [11]", "simulation parameters outlined in [10]", "detailed in [13]", "found in [14]"). The capacity and DMT advantages claimed in the text cannot be verified without these parameters, and it is unclear whether the SPDA baselines use λ/2 spacing or undersampled arrays. The paper should specify aperture size, antenna spacing, SNR, number of users, and channel model for each figure, and should add a λ/2-spaced SPDA baseline to every comparison.
  3. [Sections III-D, IV-A, IV-B] The numerical results assume "an ideal CAPA capable of fully supporting analog EM beamforming" and repeatedly state "The impact of EM mutual coupling is omitted". Given that Section II emphasizes physical CAPA implementations, the idealized model is an acknowledged limitation, but it is load-bearing for the performance claims. The paper should either include a robustness study with mutual coupling and losses, or explicitly restrict the abstract's superiority claim to ideal CAPAs.
  4. [Sections IV-A2 and IV-B] The multiuser capacity and DMT results are imported from self-citations ("Recent findings in [11], [12] indicate..." and "our previous work examined the DMT"). Because [11] and [12] are early-access papers and [14] is an arXiv preprint, and because no derivations or code are provided in this manuscript, the reader cannot independently assess the correctness of the imported results. The authors should either include the key derivations in an appendix or clearly present these as survey citations with appropriate caveats.
minor comments (5)
  1. [Abstract] The phrase "superior wireless transmission capabilities to SPDAs" should read "superior wireless transmission capabilities to those of SPDAs."
  2. [Section I.B] The bullet "Enhanced Computation Efficiency" claims that optimizing a continuous function is "computationally more efficient" than optimizing high-dimensional matrices, but this is non-obvious and unquantified; provide a complexity comparison or cite a concrete result.
  3. [Section III.A] The statement that half-wavelength sampling in the wavenumber domain "closely approximates the true values with negligible errors" needs either a precise error bound or a reference to where such a bound is established.
  4. [Section IV-A2] The sentence "the MAC-BC duality in this study relies on heuristic assumptions and cannot be generalized to scenarios with more than two users" is a significant limitation and should be restated in the concluding remarks as an open problem.
  5. [Table I] The "Frequency Selection" entries (Strong/Moderate/Weak) are qualitative; define the criterion or cite a quantitative comparison to make the table informative.

Circularity Check

2 steps flagged · score 6.0 of 10

Performance-gain claims are imported from the authors' own companion papers; the DMT and multiuser-capacity evidence reduces substantially to self-citation, though some independent content remains.

  1. self citation load bearing [Section IV-B, Diversity and Multiplexing Gains (Fig. 4, Ref. [14])]
    "For instance, our previous work examined the DMT of two CAPAs under isotropic Rayleigh fading [14]. The findings reveal that the EDoF of the radiation operator scales proportionally with the aperture size of the CAPAs and inversely with the wavelength. ... However, for SPDAs with antenna spacing larger than half the wavelength, CAPAs demonstrate a clear advantage in the DMT performance, as illustrated in Fig. 4(a)."

    The paper's key DMT/EDoF comparison is not derived, tabulated, or reproduced in this article. The text explicitly attributes the result to the authors' own prior work [14], and the figure caption states that the parameters can be found in [14]. The conclusion that 'CAPAs demonstrate a clear advantage' is a restatement of that self-cited result, so the load-bearing support for the performance-gain claim is a self-citation chain rather than an independent derivation present in this paper.

  2. self citation load bearing [Section IV-A2, Multiuser Channel Capacity (Fig. 3(b)-(c), Refs. [11]-[13])]
    "Recent findings in [11], [12] indicate that MMSE beamforming for CAPA-based MACs can be computed by solving a Fredholm integral equation with a separable integral kernel. ... The capacity of CAPA-BCs was explored using DPC-duality encoding for the two-user case in [13]. ... These figures demonstrate that CAPAs achieve larger capacity regions than SPDAs in both MAC and BC scenarios."

    The two-user MAC/BC capacity regions are not computed here; the caption says 'the simulation parameters are detailed in [13]', and [13] shares three present co-authors, while [11] and [12] are by the same CAPA group. The claimed 'larger capacity regions' are therefore imported from companion papers rather than established by an argument contained in this article. Because these figures are the quantitative evidence for the abstract's 'performance gains of CAPAs over SPDAs', the multiuser-capacity strand of the paper is load-bearing self-citation.

full rationale

The paper is a tutorial/review, so some reliance on prior work is expected. However, its headline quantitative claims of CAPA superiority in channel capacity and DMT are not derived in this article. The DMT curves are explicitly from the authors' own arXiv preprint [14], and the multiuser capacity regions are exported to [13], which shares three present co-authors, with the solution machinery credited to [11] and [12]. These are load-bearing self-citations: the text restates the cited conclusions as its own findings. The paper does retain some independent content: single-user capacity in Fig. 3(a) is parameterized by the external reference [10], and the compact-operator/Nyquist-sampling argument in Section IV-A1 is presented in the text. The paper also honestly concedes that half-wavelength-spaced SPDAs closely approach CAPA, which narrows the broad 'superior' claim of Section I.B to the undersampled regime; that overstatement is a scope/correctness concern rather than an additional circular step. Overall, the central performance-gain narrative reduces in substantial part to the authors' companion-paper chain, but not entirely, so the score is 6 rather than 8.

Assumptions & free parameters 2 free parameters · 4 assumptions · 1 invented entities

The manuscript's quantitative claims depend on an idealized continuous-aperture model and on simulations whose parameters are not disclosed here. Hardware prototypes are cited but not used as validation of the capacity or DMT gains.

free parameters (2)
  • Simulation configuration parameters (Figs. 2-4) = Not reported in this paper
    Aperture sizes, distances, SNRs, and antenna spacings are required to interpret the capacity and DMT comparisons, but captions defer them to [10], [13], [14].
  • Fourier series truncation order for radiation operator = Not reported
    Section IV-A1 says capacity is computed with a finite Fourier series expansion; the truncation order, which sets the effective DoFs, is not given.
assumptions (4)
  • domain assumption The CAPA radiation operator is analytic and square-integrable, hence compact and Hilbert-Schmidt decomposable.
    Invoked in Section IV-A1 to justify SVD, degenerate kernel approximation, and water-filling capacity. No proof or physical validation is offered.
  • domain assumption The wavenumber-domain channel of a CAPA is band-limited, and half-wavelength sampling in that domain gives negligible error.
    Used in Section III-A for discretization and in Section IV-B to equate the Nyquist number with the effective DoFs.
  • domain assumption Optimal CAPA beamformers for spectral efficiency lie in the subspace spanned by the users' spatial responses.
    Stated in Section III-C with citation [12]; no derivation appears in this paper.
  • domain assumption Ideal hardware can realize a lossless, fully controllable continuous current distribution with mutual coupling omitted.
    Fig. 2(c) assumes an ideal CAPA capable of fully supporting analog EM beamforming; Figs. 2-4 omit EM mutual coupling, a strong idealization for electrically large surfaces.
invented entities (1)
  • Ideal CAPA with lossless, fully controllable continuous current distribution
    purpose: Serves as the model for all beamforming and capacity simulations; allows functional optimization instead of discrete matrix optimization.
    The paper reviews hardware prototypes such as Kymeta and Pivotal Commware, but reports no end-to-end CAPA measurements. The performance claims are computed under an ideal model with mutual coupling omitted.

how reviews work

0 comments
Cite this review

Pith. "Pith review of CAPA: Continuous-Aperture Arrays for Revolutionizing 6G Wireless Communications." pith.science (2026). https://pith.science/paper/TNLGKLSD

@misc{pith2026241200894,
  author       = {Pith},
  title        = {Pith review of: CAPA: Continuous-Aperture Arrays for Revolutionizing 6G Wireless Communications},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/TNLGKLSD}},
  note         = {Machine review of arXiv:2412.00894}
}
read the original abstract

In this paper, a novel continuous-aperture array (CAPA)-based wireless communication architecture is proposed, which relies on an electrically large aperture with a continuous current distribution. First, an existing prototype of CAPA is reviewed, followed by the potential benefits and key motivations for employing CAPAs in wireless communications. Then, three practical hardware implementation approaches for CAPAs are introduced based on electronic, optical, and acoustic materials. Furthermore, several beamforming approaches are proposed to optimize the continuous current distributions of CAPAs, which are fundamentally different from those used for conventional spatially discrete arrays (SPDAs). Numerical results are provided to demonstrate their key features in low complexity and near-optimality. Based on these proposed approaches, the performance gains of CAPAs over SPDAs are revealed in terms of channel capacity as well as diversity-multiplexing gains. Finally, several open research problems in CAPA are highlighted.

Figures

Figures reproduced from arXiv: 2412.00894 by the authors.

Figure 1
Figure 1. Illustration of a CAPA prototype and three types of CA [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Illustration of CAPA beamforming. For Fig. 2(a) to 2( [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. The single-user capacity and the multiuser capacity [PITH_FULL_IMAGE:figures/full_fig_p007_3.png] view at source ↗
Figures from the paper (1 more)
Figure 4
Figure 4. Figure 4: The diversity and multiplexing gains and the ergodic [PITH_FULL_IMAGE:figures/full_fig_p007_4.png]

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Implicit Neural Representation for Multiuser Continuous Aperture Array Beamforming

    eess.SP 2026-03 conditional novelty 6.0 of 10

    BeamINR, a WMMSE-structured GNN INR, nearly matches functional WMMSE sum rate for multiuser multi-CAPA beamforming with far lower inference latency and better scale/frequency generalization than prior INRs.

  2. DOA Estimation via Continuous Aperture Arrays: MUSIC and CRLB

    eess.SP 2025-07 conditional novelty 6.0 of 10

    A MUSIC algorithm and Cramér-Rao bounds are developed for DOA estimation with continuous aperture arrays, with simulations showing near-CRLB accuracy.

  3. Optimal Beamforming for Multi-User Continuous Aperture Array (CAPA) Systems

    cs.IT 2024-11 conditional novelty 6.0 of 10

    The paper derives the optimal multi-user beamforming structure for continuous aperture arrays and provides a globally optimal algorithm plus near-optimal MRT, ZF, and MMSE designs.

  4. Continuous Aperture Array-Assisted Integrated Communication and Navigation in LEO Satellite Constellations

    cs.IT 2026-07 conditional novelty 5.0 of 10

    A multi-satellite CAPA ICAN design reduces average navigation CRB under rate and power constraints by projecting continuous beamformers onto a joint channel subspace and solving an iterative SDP.

  5. Electromagnetic Channel Statistics for Continuous-Aperture Array (CAPA) Systems

    eess.SP 2025-02 reject novelty 5.0 of 10

    For a CAPA under isotropic scattering, the received SNR is approximately a weighted sum of DOF=2L/lambda independent exponential random variables, yielding closed-form SNR and capacity expressions.

Reference graph

Works this paper leans on

15 extracted references · 10 canonical work pages · cited by 5 Pith papers

  1. [10]

    Wavenumb er-division multiplexing in line-of-sight holographic MIMO communica tions,

    L. Sanguinetti, A. A. D’Amico, and M. Debbah, “Wavenumb er-division multiplexing in line-of-sight holographic MIMO communica tions,” IEEE Trans. Wireless Commun. , vol. 22, no. 4, pp. 2186–2201, Apr. 2023

    2023

  2. [13]

    A primer on near- field communications for next-generation multiple access,

    C. Ouyang, Z. Wang, Y . Chen, X. Mu, and P . Zhu, “A primer on near- field communications for next-generation multiple access, ” Proc. IEEE , vol. 112, no. 9, pp. 1527–1565, Sep. 2024

    2024

  3. [14]

    Diversity and m ultiplexing for continuous aperture array (CAPA)-based communication s,

    C. Ouyang, Z. Wang, X. Zhang, and Y . Liu, “Diversity and m ultiplexing for continuous aperture array (CAPA)-based communication s,” arXiv preprint arXiv:2408.13948, 2024

    arXiv 2024

  4. [11]

    Beamforming optimizati on for continuous aperture array (CAPA)-based communications,

    Z. Wang, C. Ouyang, and Y . Liu, “Beamforming optimizati on for continuous aperture array (CAPA)-based communications,” IEEE Trans. Wireless Commun., Early Access, 2025

    work page 2025

  5. [12]

    Optimal beamforming for multi-user continuous ap erture array (CAPA) systems,

    ——, “Optimal beamforming for multi-user continuous ap erture array (CAPA) systems,” IEEE Trans. Commun. , Early Access, 2025

    work page 2025

  6. [1]

    Smart radio environments emp owered by reconfigurable intelligent surfaces: How it works, state of research, and the road ahead,

    M. Di Renzo, A. Zappone, M. Debbah, M.-S. Alouini, C. Y uen , J. De Rosny, and S. Tretyakov, “Smart radio environments emp owered by reconfigurable intelligent surfaces: How it works, state of research, and the road ahead,” IEEE J. Sel. Areas Commun. , vol. 38, no. 11, pp. 2450–2525, Nov. 2020

    work page 2020

  7. [2]

    Reconfigurable holographic surfaces for future wireless c ommunica- tions,

    R. Deng, B. Di, H. Zhang, D. Niyato, Z. Han, H. V . Poor, and L . Song, “Reconfigurable holographic surfaces for future wireless c ommunica- tions,” IEEE Wireless Commun., vol. 28, no. 6, pp. 126–131, Dec. 2021

    work page 2021

  8. [3]

    Dynamic metasurface antennas for 6G extreme ma ssive MIMO communications,

    N. Shlezinger, G. C. Alexandropoulos, M. F. Imani, Y . C. E ldar, and D. R. Smith, “Dynamic metasurface antennas for 6G extreme ma ssive MIMO communications,” IEEE Wireless Commun. , vol. 28, no. 2, pp. 106–113, Apr. 2021

    2021

Show all 15 references
  1. [4]

    Optically upcon- verted, spatially coherent phased-array-antenna feed net works for beam- space MIMO in 5G cellular communications,

    D. W. Prather, S. Shi, G. J. Schneider, P . Y ao, C. Schuetz, J. Murakowski, J. C. Deroba, F. Wang, M. R. Konkol, and D. D. Ross, “Optically upcon- verted, spatially coherent phased-array-antenna feed net works for beam- space MIMO in 5G cellular communications,” IEEE Trans. A...

    2017

  2. [5]

    Simple relations derived fom a phased-arra y antenna made of an infinite current sheet,

    H. Wheeler, “Simple relations derived fom a phased-arra y antenna made of an infinite current sheet,” IEEE Trans. Antennas Propag. , vol. 13, no. 4, pp. 506–514, Jul. 1965

    1965

  3. [6]

    Holographic beam forming and MIMO,

    E. J. Black, “Holographic beam forming and MIMO,” Pivotal Commware, Tech. Rep., 2017. [Online]. Available: https://pivotalcommware.com/wpcontent/uploads/2019/10/HBF-vs-APA-White-Paper-2019

    2017

  4. [7]

    Full duplex SA TCOM ESA with switchable polarization and wide tun able bandwidth using a tripleband metasurface aperture,

    M. Sazegar, I. Nassar, C. Eylander, A. Momeni, and R. Stev enson, “Full duplex SA TCOM ESA with switchable polarization and wide tun able bandwidth using a tripleband metasurface aperture,” in 2022 IEEE Int. Symp. Antennas Propag. and USNC-URSI Radio Sci. Meeting (AP - S/URSI)...

    2022

  5. [8]

    Interdigital waveguide gr ating antenna array for an optical phased array,

    Y . Y uan, C. Jiang, and J. Zhu, “Interdigital waveguide gr ating antenna array for an optical phased array,” Appl. Opt. , vol. 63, no. 28, pp. 7370–7377, Oct 2024. [Online]. Availabl e: https://opg.optica.org/ao/abstract.cfm?URI=ao-63-28-7370

    2024

  6. [9]

    Morgan, Surface Acoustic W ave Filters: With Applications to Elec- tronic Communications and Signal Processing

    D. Morgan, Surface Acoustic W ave Filters: With Applications to Elec- tronic Communications and Signal Processing . New Y ork, NY , USA: Academic, 2010

    2010

  7. [15]

    El Gamal and Y .-H

    A. El Gamal and Y .-H. Kim, Network Information Theory . Cambridge, U.K.: Cambridge Univ. Press, 2011

    2011

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.