material: special tool steel, hardened and tempered surface finish: chrome plated according to EN12540 Tool also fits the disc brake rotor nuts with 16 external notches. The open bottom bracket wrench is used to remove and install Shimano® Hollowtech II, Campagnolo® Ultra-Torque and Power Torque, Race Face®, FSA®, SRAM®, Truvativ®, Chris King® bottom brackets as well as many and others. The 1609/2HOBBY wrench also fits on the external centerlock disc nut.