5.56 .223  Universal AR-15 M4 M16 Rifle Gun Barrel Triple Picatinny Rails Mount Metal Clamp Accessories

Length: 65mm (2.6 inch);

Diameter: 17.6mm (0.7 inch)

Weight (net): 100g (3.5 ounce)

High-durability aluminum alloy in black matt and beautiful complement

Shock proof can be used on real fire caliber

With four pieces of half rounds (metal), one round for installation and the other is for 

spare