The Remo Powermax Marching Bass Drum Crimplock Head features a single ply of 10-mil ultra white film with a 7.5-mil underlay and a floating internal muffling ring. The PowerMax is the ultimate in powerful bass with maximum projection, tone and control. Crimplock heads feature a profiled hoop design which provides better tuning capability at higher tensions. The outer edge of the hoop is profiled over the glue channel, creating rigidity, and higher strength. These heads are typically found in drum corps, pipe band, and marching applications.