Sprocket Spacer. Spider Adapter.TophatWasher. No matter what you call it, you probably need it, to make your sprocket fit your BB spindle properly. These go on the back side of the sprocket, and are made of steel. These are not actually needed for Profile Chainring Spiders, which fit flush on a 19mm crank spindle.

A. Silver–22.2mm to 19mm–For 5mm thick chainwheels and spiders

B. Gold–23.8mm to 19mm–For older “one piece” chainwheels

C. Black– 22.2mm to 19mm–For 6mm and thicker chainwheels

Please note the 22.2mm adaptors with ONLY work with Profile sprockets (which are actually an imperial 7/8 bore) ie/ It will not fit into a metric22mm bore.