The CeramicSpeed Oversized Pulley Wheel System provides optimization and increased efficiency of the rear derailleur through its extremely low-friction bearings and unique overall design.Features a 13-tooth upper and 19-tooth lower, aluminum pulley wheels with Grade 3 Silicon Nitride balls to provide absolute optimization of the rear derailleurRobust cage crafted from polyamide and carbon fiber for durability and light weightIncludes hardened steel bearing racesCompatible with Record mechanical, Record EPS, Super Record mechanical, Super Record EPS, Potenza mechanical, and Chorus (fits up to 32t cassette)For Campagnolo rear derailleur models that do not feature a B-limit adjustment, it may not be possible to fit a 32t cassette successfully on some bikesNot compatibile with the Campagnolo 12-speed Record and Super Record derailleurs