20 BASS DRUM HEAD MADE USING TWO PLIES OF 6.5MIL FILM. AN INTERNAL OVERTONE CONTROL RING AND A REMOVABLE MUFFLE RING COUPLED WITH DRY-VENTS WORK EXTREMELY WELL WITH AND WITHOUT A MICROPHONE. AN INTERNAL OVERTONE CONTROL RING AND A REMOVABLE MUFFLE RING COUPLED WITH DRY-VENTS WORK EXTREMELY WELL WITH AND WITHOUT A MICROPHONE. VERY VERSATILE HEAD FOR ALL MUSIC GENRES; A TRUE WORKING DRUMMERS CHOICE. ALSO AVAILABLE IN A FROSTED VERSION. ALL EVANS DRUM HEADS ARE DESIGNED, ENGINEERED AND MANUFACTURED IN THE USA.