Burgtec Thick-Thin Direct Mount Chain Ring - Shimano Direct Mount - 3mm Boost - Round - Deep Blue - 12 Speed Shimano - 30TKeep that chain in place where it should be with a Burgtec Thick Thin Chain Ring. Designed with a proven thick thin tooth profile for improved chain retention. Who's this item for: Riders who use 1x drivetrains and are looking for superior chain retention as well as durability. Weight: 0. 08g Pros: Wide range of tooth options. Works for 9, 10, 11, and 12 speed setups. Great build quality. Cons: Oval options not available in all mounting types.