Heckler & Koch MR556 A4 Upper Receiver, 223 Remington/5.56 NATO, 16.5" Barrel, Threaded 1/2X28, M-LOK Handguard, Anodized Finish, Black, Fits AR-15 Lower Receivers, Includes Bolt Carrier Group, Charging Handle, Buffer Weight and Buffer Spring 51000384Includes Bolt and Buffer M-Lok Handguard • Finish: Matte Black • Barrel length: 16.5" • 17.76 Free-Float LVOA Rail/ Ambi Bolt Release

Heckler & Koch MR762 A4 Upper Receiver, 308 Winchester/7.62 NATO, 13" Barrel, Threaded 5/8X24, M-LOK Handguard, Anodized Finish, Black, Adjustable Gas Block, Includes Bolt Carrier Group, Buffer Weight, and Buffer Spring 51001919Includes Bolt and Buffer M-Lok Handguard • Finish: Matte Black • Barrel length: 13" • 17.76 Free-Float LVOA Rail/ Ambi Bolt Release

The VP9 SK Optics ready slide quickly and easily converts a standard VP9SK OR VP9SK-B to an optics ready platform. Just install your existing barrel and recoil spring. - VP9SK Optics ready slide includes: - Cocking supports - Complete firing pin assembly - Cover plate for optics cut - Suppressor height sights. Black serrated rear and high contrast front sight. - The Suppressor Height sights are specific for lower 1/3 co-witness with a mounted RMR. Other sights may vary.