CMMG, Zeroed Lower Parts Kit, MK3, Lower Receiver Parts Kit with Ambi Safety Selector, Fits AR10, Black WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov. Bolt catch, Bolt catch screw-in pin, Bolt catch plunger, Bolt catch spring Trigger, Trigger spring Disconnector, Disconnector spring Hammer, Hammer spring Trigger/hammer retaining pins Ambi-Safety, detent, spring, and screw Magazine catch, spring, & release button Pivot/takedown pins, detents, & springs A2-style pistol grip/grip screw & washer Buffer retainer/spring All the parts you need to get started on your Mk3 build in convenient color-coded packets to simplify assembly. Compatible with CMMG(R) Mk3 and most LR-308 type lowers.