These are the replacement drive shaft spacers for the Associated RC10GT series of trucks. The spacers go on the #6571 drive gear shaft assembly and help reduce the back-and-forth play of the shaft. The package comes with 4 spacers. They are made of metal. Four metal Drive Shaft Spacers 1/4" Outer diameter 3/16" Inside diameter 7-20-94 KrH ir/le &