Older model receiver made when DSA had optimal quality control. Sought after SPR model lower which eliminates the rear sight and provides a picatinny rail. Older style quad rail handguard. Upgraded gas block eliminating front sight providing a picatinny rail. DSA long picatinny dust cover. It’s a flat top from front to back! Installed is the DSA improved side folding, full adjustable stock. I have the DSA suppressor gas plug as well as the standard plug. Barrel is 16 inches. Dead Air flash hider. Comes with a single mag. Optic not included.