You can find the Phase 5 LittleBoy Hex Brake 5.56 here.

The Phase 5 LittleBoy Hex Brake for 5.56 is a compact version of the original Fatman Hex Brake. The LittleBoy has 1 large baffle to deflect the gases and reduce the overall recoil felt by the shooter. In addition to being a muzzle brake, the LittleBoy Hex has great styling as well. Includes (1) crush washer.

Specs:

• Caliber: .223/5.56
• Threading: 1/2x28 TPI (Threads per Inch)
• Mil-Spec Black Parkerized finish
• Length: 2.5"
• Width: 1.26"
• Weight: 5.3oz