It's just a board that I put across my power rack, with two pulleys attached with s-hooks and some cord. Then a long piece of cord attached to a leather sling on one end and a clip on the other to loop through the weight.
It felt a little off when I first made it (at that time it was attached to the rafters in my old basement), as though it wasn't deloading how one would expect. So I don't know if it got broken in a bit, or I just got used to the way it feels. But if you can put 10 lbs on it and lift whatever object, then you can work your way down until eventually you don't need it.