I think it's different. The one I was referring to is the one made by Blaser for their rifles. I've never taken one apart but it looks similar to a cigarette packet but slightly smaller and it drops into the stock and is held in by screws. When you shake the rifle you can just hear the beads moving around. My guess is that it's just partially filled with the beads and doesn't have springs or counterbalances etc....... seems to work very well though..........