The POWERSONIC Bass Drumheads are Constructed of 2 ply 7 mil MYLAR with two specifically placed internal subsonic dampening rings with ESDS technology External Snap-on Dampening System. The two mounted ¾” internal dampening rings enhance low end without fixating trays or hard backed dampening materials to the drumhead. The unique patent pending ESDS 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. Also included is the FALAM SLAM for added attack and durability.