Shimano BB-UN300 Bottom Bracket British Thread has Super-accurate bearings for smooth operation and improved durabilityShimano BB-UN300 Bottom Bracket British Thread FeaturesA 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