before i bought this, i had a parktool casset tool. it didn't last long, the teeth wore away quickly. i bought this because i think parktool arn't what they are made out to be. any whay, when this tool arived, i compared it to the park tool. this tool has longer splines and fits better in my opinion and i had no problem removing my casset. the teeth are still intact.A*
This little tool has gotten lots of use as I was sorting out chainline on a singlespeed bodge.. I saved money on a chain whip by laying the wheel (with inflated tyre) on the ground, wrapping my old chain around the cassette, and standing on it- it works really well if you wedge your foot against the tyre!
It's a lockring remover, which means it removes lockrings.
I'd never removed a cassette before I bought this, the first time my MTB needed a new cassette I took it to the bike shop who did it for me. This time I figured I could do it. So armed with a big spanner, a new cassette, a chain whip and one of these things I set to work. Put it in place, put the QR skewer in place, applied the chain whip and cranked the spanner. A couple of sounds later as everything moved and the cassette came off easily.
Putting the new one on was even easier, just put the spanner on the lockring remover and cranked it up.