Mine is a single model Add-a-Grapple from precisionmachine.com, made in the good ole USA. They have various sizes and a decent website to show their stuff.
When I bought the tractorI had the dealer include it in the sale, along with the valving etc. for the rear remote. The dealer had never heard of the company or installed grapples on any CUTs, but after installing mine has become one of their distributors.
I asked them to put a "T" in the lines to the rear remotes so the grapple runs with the valve that controls the remotes. I've never used the remotes in 300 hours of ownership, but the grapple is used almost all the time unless I'm plowing snow. With it, I move brush, logs, manure, dead animals, barn stones, you name it. It basically lets me double the stable volume of a load of brush or manure or to pick up large objects from the seat with little or no effort on my part.
I find the addition of a homemade toothbar helps a lot with things like sheep manure (lots of hay matted into that stuff), logs, barnstones, and big field stones. I can grab onto rocks securely enough that the rear of the tractor lifts if I try to curl one that's too big, despite the 900 lb rear weight and 260 lb on the wheels. I highly recommend getting one, although since I have nothing to compare this one to, I can't say whether it's the best on the market or not. All I know is it works for me, and with a set of quick connects on the horizontal arm of the loader frame, is easy to disconnect if I want to take it off or drop the bucket.