I bought this to install disc brake rotor lockrings. It fits over the protruding end of the axel and seems much easier to use with less chance of slipping than a thin flat lock ring remover. I use it with a large Park Tool beam torque wrench . Nicely machined and finished.
The bike shop I use did not have this. YOU ARE DEAD IN THE WATER WITHOUT IT. With it, a few seconds is all it takes. Get what you need to work on the bottom bracket!
Started using disc brakes, thought I had the right tool for mounting the rotors. Did some research. This is it.