They are just two small (though cool looking) foam stickers, but if you find the correct spot to stick them, the effect is just enough to kill the longest overtone decay while still preserving the crack and ring of the snare. Also if used in conjunction with an Aquarian studio ring and put underneath it so the ring is rised a little (and so not in full contact with the head on it's entire surface), that makes it a little more lively while still dampening it enough so it works perfect when mic-ing..
