The WHISTLE TIP PVD is a blast mitigation device (BMD) for their Cherry Bomb muzzle brake. It also serves as a Cherry Bomb thread protector for the ones who don t / can t own a silencer. As you ve come to expect, the WHISTLE TIP PVD 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"