I bought this to attach onto the main beam hoop of a welded steel garage frame, intending to lift an engine on and off of a stand.Testing with my ~300# weight, it doesn't even grumble, the only reaction was a slight squeak of the strap settling into place on the shackle of the clamp.My only complaint would be that the jack screw wasn't evenly threaded into the pivots, but that was easily remedied by unscrewing it until the far end popped free, then continuing until the handle almost bound against the body of the clamp. Thread it back into the far side and it's done. Not a major issue, and honestly not something that will affect the operation of this design as it can't close far enough to hit the center of the threads and bind the nuts on the point where the threads reverse directions.