Check the listing for details. Evans EMAD Bass Drum System Bundle - 20 inch. Condition: New. Listed at 85.99 USD. Bass Drum Dampening on Your Terms When you outfit your kick with Evans EMAD Bass Drum System drumheads, you’re taking tonal matters into your own hands. Why? EMAD (Externally Mounted Adjustable Damping) System batter heads offer a pair of built-in interchangeable dampening rings that put you in charge of how much attack, focus, and lingering sustain you receive from your heads — no hardware adjustments required! This bundle, in particular, features a 10-mil, single-ply batter head that’s perfect for achieving a bright, resonant, and forward attack tone. The second piece of the equation is the 10-mil, single-ply EMAD resonant head, offering a foam-dampening ring along the outside edge of its 4-inch microphone port that works wonders for reducing the presence of unwanted overtones.