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.Features :Bolt catch, Bolt catch screw-in pin, Bolt catch plunger, Bolt catch springTrigger, Trigger springDisconnector, Disconnector springHammer, Hammer springTrigger/hammer retaining pinsAmbi-Safety, detent, spring, and screwMagazine catch, spring, & release buttonPivot/takedown pins, detents, & springsA2-style pistol grip/grip screw & washer