Great for the price.
I have only had the chance to use it a few times but it worked awesome! It definitly has a very specific purpose but it's about the only piece like it out there and you can't beat the price! I got it to keep on my climbing harness as a backup rappel and belay device. I often take amateur climbers out who don't have a belay device so when I forget to grab my main one after loaning it this rap ring comes in soo handy and it's incredibly light so I don't even notice its on my harness. It also functions as an alpine cock ring for some complex trad anchors! My only complain is that it's a bit narrow diameter for my 11mm rope. Rappelling with it is kinda slow. I guess I just like to rap fast. So if you don't have a fat rope it's awesome! I would also recommend not using it with a very small rope either cause you wont have enough friction. It might work better with a fatter biner in that situation, something like an HMS. So basically it's the best tool around for it's job just don't use it for the wrong thing!