The Shimano BB-UN300 Square Tapered is a good quality bottom bracket for traditional chain sets with super-accurate bearings for smooth operation and improved durability. It uses a maintenance-free sealed cartridge bearing assembly that keeps out dirt, mud, and water for long bearing life.A good quality bottom bracket for traditional chain setsSuper-accurate bearings for smooth operation and improved durabilityDurable, 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