The BBB Rollerboys Ceramic Jockey Wheels are made from composite material provided by EMS Swiss, with 40% glass-fiber mixture. The jockey wheels are equipped with low friction ceramic bearings for ultra-smooth glide and exceptional durability. They are also lubricated with special ceramic light oil for extra smoothness.Options:10T - Compatible with Shimano 7 and 8-speed; Campagnolo 8, 9 and 10 speed; SRAM 9.0( 97/ 98), 9.0SL( 98), 7.0( 97/ 98) and 5.0( 98/ 99).11T - Compatible with Shimano 9, 10 and 11-speed / Mega Range and Campagnolo 11 speed12T Compatible with SRAM