Arm Material: aluminum Arm Length: 165mm, 170mm, 175mm, 180mm Chainring Sizes: 28T, 30T, 32T, 34T, 36T Bolt Circle Diameter: direct mount BB Type: [recommended pressfit] BB-MT800-PA, [recommended threaded] BB-MT800 We may as well put ‘Deore XT’ in the dictionary as a synonym of 'quality'. These Shimano XT FC-M8120 Crank Arms are built for us to put them through the wringer. Seen on our cross-country and enduro bikes, they’re light enough for all-day trail use and durable enough for us to throw down on big park days. The newest XT offering is equipped with a cinch chainring to minimize creaking and weight while working with the latest and greatest Shimano 12-speed drivetrain systems.