20" EMAD ONYX Bass Evans™ EMAD™ series features a single ply of 10mil film providing an ideal balance of punch, power and low-end. The unparalleled industry standard Externally Mounted Adjustable Damping (EMAD) system allows the player to adjust attack and focus. The Onyx™ version is the perfect aesthetic and sonic compliment to the Onyx tom heads and Onyx bass resonant.