Precision Reflex Armalite .308 Delta Forearm 15in Black. The Delta forearms overall length is 14.75in and weights 1.25 LBS. which includes the steel barrel nut. The forearm comes with 4 rails the top rail is 8.5in and two side rails and bottom rail are all 3in in length. All the delta forearms are painted (Cerakote) with aluminum rails. The elevation of the top rail to bore center is 1.328in The barrel nut thread pitch is 17/16 x 18. Specifications for Precision Reflex Armalite Delta Forearm: Manufacturer: Precision Reflex Fabric/Material: Carbon Fiber/Aluminum/Steel Gun Make: Armalite Gun Model: AR-10 Gun Type: Rifle Gun Rail: Standard Mount Type: Rail Quantity: 1 Package Contents: Precision Reflex Armalite Delta Forearm Precision Reflex 03-071-315B: Armalite .308 Delta Forearm 15in Black