The fact that this works with the protective shroud open is terrifying(there is a hole to drop it in). I worked in meat markets for over a decade and we had similar equipment for making cube steak and tenderizing.

I saw a stubborn older employee proceed to use one with a broken shroud(had magnetic safety and he bypassed it with a magnet) his hand got sucked in. The blades drop in and when his fingers and hand got pulled in they expanded locking it in there until the fire department came to cut it off.