Hinged muffling pad on one side with a smaller one on the other for use with smaller drums. Unique plastic gate attaches to the top of the pad and can be adjusted to control the length of resonance or sustain. The closer the gate is to the damping pad, the shorter the sustain.
Unnecessary? Think back to the last time you tried to muffle drums for a recording gig. Having the right pads on hand can make a massive difference. Put it in the cart.