The Remo power sonic bass drumheads are constructed of 2 ply 7 mil Mylar with two specifically placed internal subsonic dampening rings with ends technology external Snap-On dampening system. The two mounted internal dampening rings enhance low end without fixating trays or hard backed dampening materials to the Drumhead. It gives the drummer controlled mid range and low end for the most powerful bass drum sound thats it, right out of the box! The unique patent pending ends system employs snaps mounted directly to the Drumhead to eliminate the possibility of vibration. This allows you to easily customize your muffling, feel and sustain for different playing situations by snapping the strategically placed weighted pillow to the Drumhead.