Precision Reflex .308 SPR Armalite Receiver Top Rail System 14 inch Black. This rail has a full 1913 rail across the top. Rails come with mounting screws for attachment to forearm rail. The rail is 21in in length. Add .450in to the elevation of the receiver. There are 3 cross bolts that tie the top rail to the receiver and 4 #10-32 socket head screws and a bar nut that secures top rail to forearm. Top rail is designed to work with PRI round 308 forearms. This forearm is designed to work with AR10 receivers or receivers that are 1.328in off bore center to top of receiver. Specifications for Precision Reflex .308 SPR Armalite Receiver Top Rail System: Manufacturer: Precision Reflex Color: Black Finish: Hard Coat Anodized Fabric/Material: Aluminum Cant: 0 MOA Gun Make: AR Platform Gun Model: AR-10 Width: 1.325 in Height: 0.475 in Condition: New Features of Precision Reflex 14 inch .308 SPR Armalite Top Rail System: Rail is constructed of T6 6061 hard coated black anodized aluminum This rail has a full 1913 rail across the top Rails come with mounting screws for attachment to forearm rail The rail is 21" in length Add .455" to the elevation of the receiver There are 3 cross bolts that tie the top rail to the receiver and 4 #10-32 socket head screws and a bar nut that secures top rail to forearm Top rail is designed to work with PRI round 308 forearms This forearm is designed to work with AR10 receivers or receivers that are 1.328" off bore center to top of receiver. Package Contents: Precision Reflex .308 SPR Armalite Receiver Top Rail System Precision Reflex 03-072-SPR-15A: .308 SPR Armalite Receiver Top Rail System 14 inch Black