Luth-AR Lower Parts Kit - Builder - AR15. The basic kit has a good cross section of parts to build with +- a few extra to make sure you have everything you need. These kits do not come with the receiver extension or buttstock but those parts can be added as an extra item to your order. Features a clean no-assist ejector a good solid locking bolt useful pin recesses and good bolt catch springs. Parts are new but the bag is old :(. Specifications for Luth-AR Lower Parts Kit - Builder: Manufacturer: Luth-AR Color: Black Fabric/Material: 17-4 SST/Mil-Spec Steel Gun Make: AR Platform Gun Type: Rifle Condition: New Package Contents: Luth-AR Lower Parts Kit - Builder Luth-AR LRPK-BLDR: Lower Parts Kit - Builder - AR15