All the parts you need to get started on your Mk3 build in convenient color-coded packets to simplify assembly. Compatible with CMMGMk3 and most LR-308 type lowers. Check out our LPK Install resource article for an interactive assembly video and in-depth breakdown. Combine this kit with a Buttstock or Brace kit to complete your lower group. All CMMG products come with our Lifetime Quality Guarantee.Kit Includes:Bolt catchBolt catch screw-in pinBolt catch plungerBolt catch springTriggerTrigger springDisconnectorDisconnector springHammerHammer springTrigger/hammer retaining pinsSafety, detent, & springMagazine catch, spring, & release buttonPivot/takedown pins, detents, & springsA2-style pistol grip/grip screw & washerBuffer retainer/spring**Not all 308 lowers are the same. Our kit is designed to work with our lowers and are "Mil-Spec". We would recommend checking with the manufacturer of your lower for compatibility of parts if you are not using our receiver**