This is a CMMG Lower Parts Kit known as the 308, model 38CA6DC.
All the parts you need to get started on your next Mk3 build. Combine this kit with a buttstock kit to complete your lower group. Compatible with CMMG Mk3 Lowers and most LR308 type lowers.
Features:
All parts meet or exceed mil-spec
CMMG Mk3 Lowers and most LR308 type lowers