Introducing Port Hole Protector Rings and Bass Drum Head Cutter. Gibraltar protector rings come in white, black, and chrome finishes and are designed to protect the ported hole cut into your bass drum head. Available in 4 and 6 inch sizes, these two piece rings snap onto both sides of the bass drum head providing extra protection. Optional head cutter is also available. Features: Enhances sound and allows for microphone placement in your bass drum Two piece protector rings sandwich the bass drum head for solid hold and protection.