Bass Drum O's Hole Cutter Replicating the original bass drum hole reinforcement, these have a snap on design and are available in different sizes and colors to suit your application The Bass Drum O's Hole Cutter accurately cuts circular sound holes in your bass drum resonant head for venting, porting and microphone access The Bass Drum O's Hole Cutter accurately cuts circular sound holes in your bass drum resonant head for venting, porting and microphone access