The really huge ones are, but I'm in the corporate entertainment biz, and when we're rigging for a large show the motors we use are more like kix's. Actually, they're attached to the lighting/speaker rigs and just the chains go up to the ceiling. The one thing that I don't see, is the gate for the hook. Is it there and I just can't see it at this resolution? Without THAT, anything attached to the hook could come bouncing out and THAT could smash down on peoples heads!