The part under the seat, sized by its bolt pattern
The plate that bolts under a chair seat and carries the tilt, swivel and height controls, published with the two dimensions that decide whether it fits — the cylinder hole and the bolt pattern.
Skelang seat tilt and swivel control mechanism
Best for: A chair whose seat and base are sound but whose height lever or tilt has stopped working.
When a chair stops holding its height or will not lock its tilt, the fault is in a steel plate the size of a hand bolted under the seat — and this is that plate. It carries the gas cylinder socket and the levers, and it can fail while the seat, the base and the casters are all still good.
Fit is decided by two measurements and the listing publishes both: a gas cylinder hole of 1.57 in and a mounting hole pattern given as 10.2 by 6 in. The bracket is stated at 0.1 in of steel. That is the right information — the same standard the Frassie and MASTERY MART bases meet by publishing their cylinder hole and caster sockets.
The one problem is that the two bolt-pattern statements on the page do not match. The product name says 10.2 by 6 in; the size bullet says “6” - 10” bolt pattern” and then refers you to the third photograph. Those are the same numbers arranged as a rectangle in one place and as a range in the other. And nowhere does the listing publish a load rating, on the single part of a chair that carries the whole of the sitter — while two bases a few rows down this shelf claim 2,500 lb each.
Read on the day this page was built: $22 at the American Amazon shop.
Read from Keepa on the day this page was last revised; stock and price both move without notice.
Best for: A chair whose seat and base are sound but whose height lever or tilt has stopped working.
Prices quoted in this text were read on 2026-10-13. The live price is at the top of the page.
The listing gives it twice in two forms. The product name ends "Mounting Hole Dimension: 10.2"×6"(L×W)", and the size bullet says "the tilt control mechanism is 6" - 10" bolt pattern (Check the third image for size information before order)". Read together, the holes are 10.2 in apart one way and 6 in the other — but the bullet’s phrasing reads like a range, and the listing itself sends you to an image rather than settling it. Measure your own plate in both directions before ordering.
They are the two halves of the same repair and they fail for different reasons. The mechanism is the plate bolted under the seat that holds the gas cylinder and carries the tilt and height levers; the base is the five-star spider the casters go into. A chair that will not hold its height has a cylinder or mechanism fault; a chair that wobbles or has a cracked arm has a base fault. This shelf now carries both, and the figure that matters is different for each — bolt pattern here, base diameter and cylinder hole there.
Rollerblade-style casters sold on a lifetime warranty and an origin story rather than a specification — there is no load rating, stem size or wheel diameter on the listing.
Best for: A buyer who would rather have a warranty they can call on than a number they cannot check.
A four-part kit — base, gas cylinder, bottom plate and five casters — that publishes a 350 lb capacity and 110 lb per caster: the lowest figures on this shelf, though five casters at 110 lb make 550, not 350.
Best for: A chair where more than one thing has failed, and the seat is the only part worth keeping.
A complete 28 in base that ships with both casters and bell glides, so the same chair can be made to roll or to stand still.
Best for: A chair that should stop rolling — a stool at a bench, or a chair on a sloping floor.
A 36 in two-tier converter on a steel spring lift with thickened square tubing, rated 33 lb and 4.4 lb — and the only converter here with no height range on its listing.
Best for: A dual-monitor desk where a spring lift is wanted and the height can be checked on delivery.
A two-tier converter on a steel-wire mechanical spring rather than a gas cylinder, publishing both surface dimensions and a separate rating for each tier.
Best for: A standard desk where the lift mechanism should have nothing in it that can leak.
A pneumatic squeeze-handle converter on an aluminum frame, rated to 33 lb — and the only listing on this shelf that names the material of its own work surface.
Best for: A converter adjusted several times a day, where a squeeze handle beats a spring you fight.