Customizable sounds with great durability. Evans MX Marching Bass 2-Ply series includes a unique tone damping system that can be manipulated by applying individual felt arcs (included) to enhance articulation and focus low-end for both indoor and outdoor marching. Evans MX2 BD18MX2W 18 Inch Marching Bass Drum, White 2-ply construction (7.5 mil 2x). Adjustable, removable felt arcs for customizable dampening. Available in sizes 16 – 32 inches