I used one for a year and it worked great for me. I really liked the way that it works, but I had a noise issue with mine that I didn't care for so I switched to a Drop Zone and love it. The Mach 4 works kinda like a mouse trap, you cock the rest ( there is a pin on the shaft for the launcher arms that fits in a slot on a pendilum weight inside the covered box) and the torque from the bow being shot drops the rest. I took mine apart to see why it was so loud is how I know. The rest worked flawlessly for me, but I am a noise freak so I switched.

Chris