Shimano BB-UN300 68mm Shell Square Taper Bottom Bracket English Thread has Super-accurate bearings for smooth operation and improved durability - Super-accurate bearings for smooth operation and improved durabilityFeaturesA good quality bottom bracket for traditional chainsetsDurable, hard-wearing sealed cartridge bottom bracket with square tapered spindle fittingMaintenance-free sealed cartridge bearing assembly keeps out dirt, mud, and water for long bearing lifeFast and easy installation without adjustmentNarrow body allows clearance for cable routing under the bottom bracket