Narrow Wide tooth profiling ensures ultimate chain retention. Attaches as part of the RF Cinch system (using common Park BBT-22 bottom bracket tool) - allowing to switch between DM rings/spiders with ease. Utilizes RF proprietary spline design7075-T6 aluminum, aerospace grade strength. Stiff 4mm plate thickness to transfer loads without flexing. Compatible for 9, 10, 11 and 12 speed.