Designed for the Shimano 12 speed mountain bike derailleurs, these pulleys maximize the tooth count to reduce friction The specific 14 tooth upper and lower pulley wheels are built to last: aluminum cogs, serviceable bearings to resist the most challenging mountain bike conditions Compatible with Shimano 12 speed mountain bike derailleurs Cross seals only Shimano 12sp Black/BlueUPC/EAN/GTIN: 735201956060