Universal brass instrument valve stem or finger button, cork washers, each purchase gets a set of 3, you choose your size. see my item ID# 275667836939 for thicker stem corks typically used on Conn Tubas & Sousaphones, licke the 20K.
Cork 1/2" OD x 1/16" thick x 7/32" ID. Most common cornet & trumpet.
Cork 9/16" OD x 3/32" thick 7/32" ID. Most common low brass.
Cork 9/16" OD x 1/8" x 7/32" ID. Many horns needing thicker cork.