LanTac USA LLC Raven AR-15 Billet Builder Set, Anodized Finish, Black, Includes Upper/Lower Receiver and 13.5 Spada M-LOK Rail with Mounting Hardware 01-RV-BSET-13-RAVEN The Lantac AR-15 builder set includes an upper and lower receiver, along with an M-LOK handguard. Their Raven billet receiver set is machined from certified 7075-T6 aluminum and finished with Type 3 Hardcoat. The lower receiver features a 45-degree BAD Safety Selector cut and includes an internally flared mag well to assist with loading.