Wolf Tooth MARKZERO (MK0) Bottom Brackets take performance to another level with aggressive machining, custom ceramic bearings, and intricately designed race sealing built to their exacting specifications. This design saves you watts while proving durable enough for the most intense off-road racing, inclement conditions, and are fully serviceable. MK0 components are proudly machined at Wolf Tooth HQ in Minnesota, USA. Compatible with 24mm crank spindles Installation and removal with standard 44-16 spline tool (sold separately) Includes (2) 2.5mm shell spacers and (2) 0.5mm, (2) 1mm, (1) 1mm, (1) 3mm, and (1) 5mm spindle spacers MK0 silicon nitride ceramic bearings feature custom race sealing for flawless performance against the elements and endless speed Custom polymer spindle bushings separate the bearing inner race and crank spindle to eliminate metal-on-metal contact, the leading cause of bottom bracket creaks Bushings also helps enhance bearing longevity with an interface to the bearing gutter seal for maximum weatherproofing Aggressively machined to be lighter than the competition while offering superior speed and performance in all conditions 6061-T6 Aluminum cups and AISI 52100 chrome bearing steel races hardened to Rc 60-65 with ACOSUR-ZNA corrosion resistant coating Item Specifications BB Shell Width (mm) 68 BB Shell Width (mm) 73 BB/Frame Interface English Bottom Bracket Shell I.D. 1.37 Defined Color Gray Spindle Interface Type Shimano Hollowtech II Weight 76 Wolf Tooth MK0 English (BSA) Ceramic Bottom Bracket Bottom Brackets UPC: 810159403498