6: 34mm inner top diameter

They have a nice little feature to aid with this

9/400mm: 365g

and a drastically shortened normal head on the other

This is a jersey you will reach for again and again

Burgtec Thick-Thin Direct Mount Chain Ring - Shimano Direct Mount - 3mm Boost - Round - Race Red - 12 Speed Shimano - 34T NoAusPost 6: 34mm inner top diameterKeep 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.