TheShimano Deore XT SM-CRM85 M8100/M813 Chainringfeatures aDynamic Chain Engagement (DCE), which is used to hold the chain and help prevent chain jump out.This is achieved by using a broader and taller tooth profile in conjunction with a special hooked leading edge and alternate profiled tooth shaping. This provides superior chain retention, lower driving sound, increased durability and keeps drag to a minimum. Shimano Deore XT SM-CRM85 M8100/M813 Chainring Features Hollow gear construction for optimized rigidity, lightweight and durability Durable teeth using a plated steel construction supported by a carbon composite (CFRP) carrier body HG 12-speed chain compatible Available in 28T/30T/32T/34T/36T