Primary Weapons Systems was formed by firearm enthusiasts in 2008. Starting out by producing muzzle devices, they tested their compensators on all different types of rifles - from M4s to AK-47s. After using both styles of rifles in testing with high round counts, the difference in maintenance needed was both astounding. From that basic realization, the PWS long-stroke piston system was born; keeping the core values of the AR-15 design, while also lessening the need for maintenance in high-volume fire situations and adverse conditions. PWS ambidextrous MK1 MOD 2-M Multi-Caliber Lower, T6 7075 Forged, Anodized, AR-15 Compatible.Features :Ambidextrous Magazine ReleaseAmbidextrous Bolt CatchLightweight DesignIntegrated Trigger GuardTrigger: Mil-Spec Enhanced, PTFE CoatedTrigger Pull Weight: 5.5 6.5 lbs.Buffer Tube: PWS Enhanced Buffer Tube with ratchet lock castle nut and end plate set with built-in QD mountBuffer: PWS Enhanced H2 Steel Body BufferFurniture: Bravo Company USA Buttstock and Pistol Grip