e*thirteen e*spec Aluminum Direct Mount Chainring 38t for Brose S Mag, Blacke*spec Direct Mount Chainrings use e*thirteen's M3 narrow wide tooth profile, which reduces weight without sacrificing chain retention. These lightweight and well designed chainrings are adapted to work with Brose S Mag eBike motor configurations. The M3 dual width tooth profile eliminates chain noise, and decreases overall system wear 53mm Boost chainline 7050 Aluminum Product Specifics Color: Black Defined Color: Black Designed for ebike: Yes