The TK1724 Shuriken pulley is the easiest member of the Shuriken family but it's not as easy as it looks - light, smooth and precise. Available in both TBT ceramic and Premium versions, the TBT version pulleys are PVD coated for long-lasting extra smoothness.Pulley wheel: 12T upper, 14T lowerCompatibility: Shimano R9100, R9150(elec.), R8000, R8050(elec.).Both long (GS) and short (SS) cages are supported.SRAM all 11-speed models are supported. 12-speed models are not supported.All Campagnolo models are NOT supported. Note: Slight derailleur sdjustment may be needed to achieve optimal performace. Check before your first ride!