If you own an external bottom bracket with 16-notch, 48. 5 or 44mm diameter cups and you plan on doing some installing, removing, or general maintenance, you owe it to yourself and your bike to pick up the Double Ended Bottom Bracket Wrench from Wheels Manufacturing. This aluminum machined and red anodized bottom bracket wrench features a tool at either end for 16-notch cups with a 44mm diameter on one side as well as a 16-notch, 48. 5mm diameter wrench on the other end. Its compatible with all current Wheels Manufacturing bottom brackets with notched cups as well as many other outboard bearing bottom brackets including Shimano, FSA MegaEXO, Campagnolo Ultra Torque, and SRAM/Truvativ.