The FERFRANS CQB Modular Muzzle Brake System is a two part system consisting of the performance muzzle brake mount + CRD (Concussion Reduction Device) which features a built in quick attach/detach mechanism.

The muzzle brake effectively mitigates felt recoil and muzzle movement and with the CRD attached does this while minimizing side blast/concussion and redirects sound to the front of the shooter. It is a two piece modular system that includes (1) very effective high performance muzzle brake and (2) a ported Concussion Reduction Device (CRD) that attaches to the muzzle brake using a quick detach mechanism. The CRD has strategically placed side ports that allow the muzzle brake to retain its compensator functionality as opposed to brake shields that cover the brake and negates its function.

With the CRD attached, recoil feels like a slight, straight to the rear push (it's a softer recoil feel, not the typical sharp kick). It is, of course, a compromise between reducing side concussion versus minimizing felt recoil. We believe we have achieved an optimal balance of sufficient brake/ compensator functionality (muzzle leveling effect) and side concussion reduction. The CRD has a quick detach/attach mechanism to allow you to easily switch back to a full brake whenever you.
Specifications:

Muzzle Brake:
Weight - 3.9 oz
Length - 2.28"
Thread Pattern - 1/2x28 or 5/8x24
Caliber - (.223/5.56) or (.308/7.62)

CRD (Concussion Reduction Device):
Length - 2.17"
Width - 1.6" Diameter
Total weight of the system combined is 10.3 ounces

Note: When CRD is attached the tip of the muzzle and CRD are flush