Evans EMAD2 series bass drum heads can withstand a pounding while still providing a warm and focused tone. This 20" head features two plys of film. The outer ply of 6.5mil and an inner ply of 10mil film work together to provide an enhanced attack, focused tone and extreme durability. The Externally Mounted Adjustable Damping (EMAD) system allows the player to adjust attack and focus by placing a foam ring around the outside perimeter of the drum head.