Evans white MS1 marching bass drum heads offer a traditional single-ply, 10mil film without muffling in order to give the widest range of damping options. The MS1 series projects warm, musical tones both indoors and outdoors and are durable, yet priced for the budget conscious. 20 inch drum head with a single ply of 10mil film. Bright and resonant tone. Traditional sound and feel. May be used with any variety of internal or external muffling techniques. All Evans drum heads are designed, engineered and manufactured in the USA.