The 1671.5/2BI-US bottom bracket wrench is two tools in one, really. The business end is a socket of sorts that allows for installation and removal of any 16 notch external bottom bracket cup with a 24mm I.D. bearing.
Unlike most other tools designed for these, the socket features a guide pin which helps to prevent cam-out much in the same way as our cassette lock ring tools. Good bottom brackets are expensive, it doesn't make any sense to run the risk of marring the finish when you're installing them. The guide pin in our tool ensures the tool can't rotate and slip off the cup.
Attached to our 1671.5/2BI-US is a 350mm handle that gives you the leverage you need to break free the most stubborn of bottom brackets. For those really stuck cups you can remove the handle and attach something even longer. Removing the handle also allows you to use a torque wrench when it's time to install the new cups.