Kgm Suppressors RS-R556A2-QD-BLK R556A2 6mm/5.56 NATO Black Nickel Alloy/Stainless Steel 1/2"x28 These models were designed to meet and exceed SOCOM specifications for full-auto firing, while enhancing rifle accuracy, providing superior repeatability, while maximizing sound suppression, and have minimal impact on a rifles operating system. Both suppressors are built to last, consisting of high-quality nickel alloy and stainless steel components that are laser welded together, ensuring an extended service life, even after enduring years of hard use