The WHISTLE TIP is a blast mitigation device (BMD) for the Cherry Bomb muzzle brake. It also serves as a Cherry Bomb thread protector for the poors who don't / can't own a silencer. As you've come to expect, the WHISTLE TIP features a taper mount for proper alignment to the Cherry Bombs and installs with any off the shelf 1-inch wrench. Specifications: WEIGHT: 2.7 oz. OVERALL LENGTH: 1.85" OUTSIDE DIAMETER: 1.16"