Narrow Wide tooth profile for better chain retention. Forged and machined 7000 series alloy with hard black anodizing for durability. Works with 1×10/11/12sp Shimano, KMC and SRAM Eagle, Flat and T-type chains. Must use a aclutcha type rear derailleur. Ex: Shimano Shadow or SRAM Type2 . Shimano compatible with both mechanical and Di2 Shimano 10/11/12sp. SRAM compatible with both mechanical and wireless SRAM 10/11/12sp. In rough terrain, or just for pure security, use of an upper guide recommended. Unauthorized online sales prohibited by manufacturer