If you're removing cassettes more than once every couple of years, spring for the Campagnolo-made tool. This doesn't fit the retaining ring precisely and I have to bang it in. Not what I want to do with Campy 10, Record and Super Record cassettes. Since I change out cassettes for training, racing, the terrain, to replace worn gears, etc. I'll have to buy the (much more expensive) Campy-made tool.
The one I have fits Campy rings (I have several Campy ringscassettes) very crudely ... I have to bang it in place with a rubber mallet, then pry it out with an open end wrench between the ring and tool. Perhaps I just got a poorly finished one. I hate doing this to a Campy ring. I'll have to spring for an (expensive) Campagnono precision made tool.