EVANS Corps Clear Marching Tenor drumheads are more durable than thinner tenor heads, featuring two plies of film--a top ply of 6.5mil and a bottom ply of 10mil. Incorporated with EVANS Level 360 Technology for ease of tuning, extended pitch range, and optimum quality of sound, the Corps Marching Tenor prolongs the life of the drumhead but also keeps it in tune longer.