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Publishes both interfaces, and claims 2,500 lb

MASTERY MART chrome-plated five-star base, 28 inch

A chrome-plated 28 in base that publishes both of the dimensions that decide fit — the 2 in cylinder hole and the 11 × 22 mm (0.43 × 0.87 in) caster sockets — under a 2,500 lb claim.

MASTERY MART matte black 28 inch five-star office chair base

MASTERY MART chrome-plated five-star base, 28 inch

  • Publishes both interfaces — a 2 in gas cylinder hole and 11 × 22 mm (0.43 × 0.87 in) caster sockets — which is what decides whether a base fits
  • Names chairs rather than claiming a percentage, including Herman Miller, gaming, desk and executive chairs
  • A 2,500 lb claim with no method, matching another base on this shelf while a third states 350 lb

Best for: A chair whose base has cracked, where the seat and mechanism are worth keeping.

≈ $40
Check price on Amazon

Specifications

Amazon reference
B07ZY36NJ1
EAN
8011577967759
Type
Five-star base, no casters or cylinder
Base diameter
28 in (70 cm)
Cylinder hole
2 in (5 cm)
Caster socket
7/16 × 7/8 in (11 × 22 mm)
Material
Chrome-plated metal, matte black finish, tubular iron reinforced with screws
Stated load
2,500 lb (1,134 kg), no method given
Base weight
Not published

A base is the one chair part where fit is unambiguous, because there are exactly two interfaces: the hole the gas cylinder drops into, and the sockets the casters push into. This listing publishes both — 2 in for the cylinder, 11 × 22 mm (0.43 × 0.87 in) for the sockets — which is more than most base listings manage and is the whole of what a buyer needs to measure.

The rest of the specification is construction rather than numbers: chrome-plated metal with a matte finish over a tubular iron structure reinforced with screws, 28 in across, which is the standard replacement diameter and the same as the two other bases on this shelf. Compatibility is claimed by naming chairs — Herman Miller among them — rather than by quoting a percentage, and the listing frames the purchase honestly as a repair at roughly a fifth of the price of a new chair.

The load figure is where this shelf stops being comparable. Two thousand five hundred pounds appears here and on another 28 in base alongside it, while a third 28 in base states 350 lb and rates its casters at 110 lb each. No listing gives a method. The construction is the part to judge; the number is the part to discount.

Availability

Read on the day this page was built: $40 at the American Amazon shop.

Read from Keepa on the day this page was last revised; stock and price both move without notice.

What holds up, and what does not

Best for: A chair whose base has cracked, where the seat and mechanism are worth keeping.

Strengths

  • Publishes both interfaces — a 2 in gas cylinder hole and 11 × 22 mm (0.43 × 0.87 in) caster sockets — which is what decides whether a base fits
  • Names chairs rather than claiming a percentage, including Herman Miller, gaming, desk and executive chairs
  • Chrome-plated metal with a matte finish on a tubular iron structure reinforced with screws
  • A 28 in diameter, which is the common replacement size and the same as the two other bases on this shelf
  • Framed as a repair — the listing puts it at a fifth of the cost of a new chair

Compromises

  • A 2,500 lb claim with no method, matching another base on this shelf while a third states 350 lb
  • No weight published for the base itself, where one base here states 22.5 lb
  • No casters or cylinder included — the sockets are empty
  • One bullet argues that an improper chair height damages floors, which is about the chair rather than the base

Prices quoted in this text were read on 2026-10-13. The live price is at the top of the page.

What buyers ask us first

What has to match for a base to fit?

Two things, and this listing publishes both: the gas cylinder hole through the hub, given here as 2 in (5 cm), and the caster socket size, given as 7/16 by 7/8 in or 11 × 22 mm (0.43 × 0.87 in). Get the cylinder hole wrong and the chair will not sit in the base; get the socket wrong and your casters will not go in. The diameter — 28 in here — decides stability and whether it clears your desk, not whether it fits.

Can a chair base really take 2,500 lb?

The number is published without a method, and it is the same figure another base on this shelf claims while a third states 350 lb for a base of the same 28 in diameter. A factor of seven between listings for the same part suggests the figures are not measured the same way, if at all. What is checkable is the construction described — tubular iron, screw-reinforced, chrome plated — and the 350 lb figure is the more plausible of the three for a part a person sits on, though none of them says how it was measured.

More chair casters

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    Five plastic-wheeled casters with the standard 7/16 by 7/8 in stem, stated to carry 1,000 lb and to leave hardwood unmarked — in the material this hub’s introduction advises against for hard floors.

    Amazon reference
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    EAN
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    In the box
    5 casters
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    7/16 × 7/8 in (11 × 22 mm)
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    2 in (51 mm), plastic
    Floors
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    Stated load
    1,000 lb (454 kg), per wheel or per set not stated
    Not compatible with
    None named
    • Publishes the stem in both units — 7/16 by 7/8 in, 11 × 22 mm (0.43 × 0.87 in) — which is what this hub’s buying tip asks for
    • States it rolls over short rugs as well as wood and tile
    • Plastic wheels, where this hub’s introduction names a rubber-coated wheel as the hard-floor upgrade

    Best for: A rug or short carpet, where plastic is the material the shelf would send you to anyway.

    ≈ $15
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    Five 2 in rubber casters on standard 11 mm (0.43 in) stems, and the only caster set in this hub to publish its load per wheel rather than a total — the Topdeep base kit is the only other part to give one.

    Amazon reference
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    EAN
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    In the box
    5 casters
    Stem
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    Wheel
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    Floors
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    Stated load
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    Not compatible with
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    • Publishes a load per wheel — 300 lb — which is the figure this hub compares; among the caster sets, the only one given that way
    • States the total as well, 1,500 lb for five, so the arithmetic is visible
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    Best for: A chair on a hard floor or low-pile carpet, where the stem has already been measured.

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    Transparent dual-wheel polyurethane casters with a published noise figure of 28 decibels and a 700 lb rating — the second most modest load claim among the caster sets here, after the Lifelong's 650 lb.

    Amazon reference
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    EAN
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    Manufacturer reference
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    In the box
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    Stem
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    Wheel
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    • A 700 lb claim with the metric equivalent given, 317.5 kg — modest beside the 1,000 to 2,500 lb figures elsewhere on this shelf
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    Best for: A shared office or a quiet room, on a chair named in the listing.

    ≈ $25
    Check price on Amazon

Elsewhere in the spares drawer

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    Amazon reference
    B07SKRJWT1
    EAN
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    Manufacturer reference
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    Coverage
    Back and seat; no armrest covers
    Back
    17.7–22.8 in wide, 27.5–31.4 in high (45–58 × 70–80 cm)
    Seat
    17.7–23.6 in wide, 17.7–22.8 in long (45–60 × 45–58 cm)
    Material
    90% polyester, 10% spandex
    Fixing
    Zips on both sides
    Care
    Machine wash cold; no bleach, no dry cleaning; iron on low heat
    • 10 per cent spandex, the highest stated proportion among the plain stretch covers here, which is what lets a cover round a contoured back
    • Zips on both sides rather than a single closure, stated to prevent shedding
    • The care instructions permit low-heat ironing, where the Smiry and GOWT covers state no ironing is needed

    Best for: A high-back chair where the cover has to stretch round a contoured backrest and stay put.

    ≈ $10
    Check price on Amazon
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    A jacquard-weave stretch seat cover that publishes all three seat dimensions it fits, including the cushion thickness — which is the figure that decides whether the elastic will reach under the pan.

    Amazon reference
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    EAN
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    Manufacturer reference
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    Amazon reference
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    EAN
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    Manufacturer reference
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    Search Amazon for this model

All chair casters