Material: special tool steel, hardened and tempered surface finish: chrome plating in accordance with the EN12540 standard The tool also fits brake discs with nuts with 16 external notches. How to use the device: The wrench is designed to remove and install Shimano Hollowtech II, Campagnolo Ultra-Torque and Power Torque bottom brackets, FSA, SRAM, Truvativ, Chris King and others.