Its a small rectangle piece of moon gel. They are for dampaning the heads. You can use on the snare toms whatever. It alows you to controll how much you want instead of studio rings that only give what they give.
you can also cut them into smaller pieces for less dampening, if desired
you can also wash them with normal soap and water if they catch too much dust and pieces of wood from your playing...i bought em and i LOVE them, it gives my set just the sound i was wanting