This looks like an Early slabside M16 upper. It has a Colt slabside small hole receiver with sights and the dustcover. The barrel started as a chrome lined 1/9 twist Bushmaster A2 goverment profile thats was turned down to A1 size from the handguard cap forward and refinished. It has an A1 delta assembly, triangular handguards, gas tube and pin. The lug has been removed and a fake threeprong flashider attached (blind pinned and welded)so it post ban legal. about 600 rounds fired. In very good condition, no bolt carrier or charging handle. $275 or best offer shipped. Paypal preferred.