This product is a set of 10 items for trumpet: - 4 slide cushion rubbers - 3 bottom cap rubbers - 3 stainless steel bottom rings The slide cushion rubbers are used to eliminate the "clunk" sound when the 1st or 3rd trigger slides are returned, and also improve the appearance. The bottom cap rubbers fill the gap created when the bottom ring is inserted into the bottom cap, and also improve the appearance. The bottom rings are designed to provide resistance to the instrument, eliminate unnecessary vibrations, and enhance projection. (Size: Outer diameter 18 x Inner diameter 8 x Thickness 1.2mm) We have put all of these together in a set, so please consider it if you are interested. Thank you. m(_ _)m * A set with brass bottom rings is also available. It seems that brass produces a softer sound, while stainless steel produces a harder sound. * Although listed for trumpet, these can also be used for cornet, flugelhorn, etc. * Additional parts and individual sales are also possible. Please contact us via the comment section. * Due to the punching process for the bottom rings, there may be burrs on the edges. Please be aware of this. * Bach trumpets have thin valve cylinders, and the bottom cap rubbers may be a little loose. Please be careful.