The 24" Evans EMAD Heavyweight Bass Drum Batter Head has two 10mil plies and the EMAD damping system that allows the attack and focus to be adjusted. The ultra durable Evans 24" EMAD Heavyweight Bass Drum Batter Drum Head is a two ply (both 10mil) head that also features the EMAD damping system - allowing for the attack and focus to be adjusted to taste. The Heavyweight heads deliver maximum durability - perfect for heavy hitters or for those that want to play safe in the knowledge that it'll be harder to put the beater through their heads! Heavyweight heads not only provide great durability but they also deliver a feel that belies it's 'heavyweight' status. Tonally they deliver a wide dynamic range and a compressed, focused attack.