The one that I have is a simple conversion and does not alter the rifle in any way. You just simply remove the floorplate, follower and spring. (Not the whole bottom metal) The detachable clip justs snaps in.
As the previous poster stated, it adds weight and is not very attractive. YMMV
The one I have I purchased off from eBay some time ago. (And, no, it's not for sale...)
I don't believe that eBay allows sales of clips now. You might try Auction Arms