I must be out of my tree for doing this, but I picked up one of these "Claw" clones from hical.ca for my SA20.  We have these on our C7A2s at work, but I was never a big fan of them.  Some have experienced snagging on their tac vests, others love them.  My opinion of these is pretty neutral but lately I've had a bout of OCD and decided my SA20 needed one of these.

It's a pretty easy installation and all you really need is a punch set, a hammer and less than five minutes of work.