This Shimano BB-UN300 bottom bracket is a solid and smooth-running square-axle bottom bracket. You can easily install the matching crank and the bottom bracket is very durable.High-quality and performance-oriented.This Shimano BB-UN300 square-axle bottom bracket from the Alivio series has a very strong and durable design, ensuring you can transfer power to your wheels with minimal resistance. The axle is made of steel, and the bearings are well-sealed. This bottom bracket is therefore durable and requires little maintenance! Specifications Bottom Bracket High-performance SHIMANO square axle bottom bracketGreater chainline stability with chainline stabilizer3 structures availableOptions: Standard, E-type, Chain GuardAdapter Material: Aluminum
