A crescent wrench is not necessarily a required item if you have other suitable tools -- I think fogrider was just listing what he uses. Some lockring tools have a hex "bolt" end, onto which you attach a crescent wrench (or a socket or other wrench), like this:


I don't use a crescent wrench either. I bought one of those tool-kits and it has a large Allen wrench that fits into the lockring tool instead (sorry, I don't have a picture handy).