I've had this for about four years now with a decent amount of use on it. It's sold by EliteFTS and made by Williams Strength, and like everything from those two it's heavy duty. The rollers have a grippy fabric over comfortable foam, and most of the attachment is powder coated with a grittier texture than my REP attachments, so I'm not worried about durability. The weight horn will chip over time from plates sliding on it, which is normal. It came with a weight pin I've never used, gravity does that job. The rubber stopper is a nice touch that keeps it from banging into itself between reps. Install takes one hand. Slide it on the post, drop the pin in, done. Removal is the same. It came with two pins but the bottom one doesn't line up with my rack and you really only need the top one. As a standing leg curl it works phenomenally. Set the height, load your weight, slide in from one side and curl one leg at a time. It's intuitive even if you've never used one before. Fair warning if it's been years since your last leg curl, go easy. I could hardly walk the next day. It's not advertised as a leg extension but it works really well as one. I keep it at the same height, put a plyo box at the edge and sit in from the side. The weight curve feels natural, not noticeably easier at the bottom than at the top. You can throw a band around the weight horn and your upright if it bothers you, but I've never needed to. For two legged extensions you do straddle the post, and the pin that secures the attachment can dig into your thighs a little when you're right up against it. Not painful, and once I get in a rhythm I forget about it. You can't do close legged extensions either. Loaded heavier it stays just as smooth, and you'll probably run out of legs before you find the weight cap. Two things to know. The side edges on mine came sharp and scratched my rack worse than an attachment should, so I filed them down and put felt tape inside the walls. Problem solved. And buying one isn't a normal checkout. You contact an EliteFTS sales rep for a quote and then it's about a six week lead time. Different post sizes or hardware carry a surcharge. Against the alternatives it wins easily. The Sorinex Mule loads weight on one side only. The small fab shop version I own never felt right for curls or extensions, both legs or single leg, so I'd skip the cheap options. Compared to a standalone leg curl machine it holds its own on price and stores away on your rack. For how well this works it's an insane value. I can't recommend it enough.
Disclosure: bought this product with their own money.