This SPR Straight top rail is a full Picatinny rail that connects the receiver to the forearm.  The 8.5" forearm rail need to be removed to install top rail.  This creates a rigid platform ideal for mounting accessories.  This rail is constructed of hard coat black anodized T6 aluminum.  Rail connects to rifle receiver with 3 cross bolts and the front of the rail connects to the forearms top rail using to screws.  Rail is 19.5" in length with an add elevation of .450".