What an ingenious idea, to provide four different beater heads in a single frum beater. The Quad Beater offers two felt surfaces (with different shapes) and two plastic surfaces (also with different shapes), provinding four different sounds (and rebounds) to your bass drum playing. The Quad Beater includes a small weight that can be slided along the shaft (or removed) to adjust to you playing style. The diameter of the shaft fits all standard drum pedals (I installed it on a Tama Iron Cobra).