The Griffin Armament’s MK1 PSD AR-15 Series represents a fully-featured carbine worthy of use as your primary carbine out of the box. Built as a system with each component working in harmony to create an incredibly soft-shooting platform suppressed or unsuppressed, while maintaining Mil-Spec tolerances for compatibility with other Mil-Spec parts on the market. The MK1 PSD features a pistol-length gas system; suppressor optimized buffer system; Griffin’s Anti-Rotation LOW-PRO Rails provide for accessories such as lights and lasers, these rails have a tab that interfaces with the upper to prevent rotation of the rail under torque.