Take to your bass drum resonant head with a Holz Port Hole Ring from Cardinal Percussion. Mic port holes are imperative when it comes to boosting your bass drum’s sound quality onstage and in the studio; without reinforcement, your reso head can start to suffer over time. Designed for seamless use with 4-inch port holes, the Holz Port Hole Ring is your solution, preventing the cutout from fraying and improving the structural integrity of the head without negatively affecting your resonant tone.