Direct Mount chainring for Shimano motors Updated M3 narrow-wide tooth profile eliminates chain noise, and decreases overall system wear while retaining chain An alloy outer dust cover helps to prevent contamination 11/12 speed. Compatible with both Shimano and SRAM 12 speed drivetrains 53mm chainline to support dropping a chinring size to take advantage of e*thirteen 9t cassette cog Model Helix R E*spec 21mm Offset Ring Type Single (Anti-Chain Drop) Mount Shimano EP8 Teeth 32 Oval/Round Round Color Black