Our GS-1 FIRE System optical mounting rail was designed for mounting a conventional-type scope on the AR/15/M16. It provides significantly longer eye relief for a proper scope/operator interface and the capability of attaching additional optical devices, such as a night vision monocular. The back of the rail has been tapered to blend with the rear of the upper receiver and is not designed to mount a BUIS flip-up rear sight. It extends 3 inches over the handguards and clears the M4 forearm. There are numerous tactical situations where an extended scope rail creates an advantage for the AR-15 or M-16 user. GG&G's scope mounting rail allows for accuracy at greater distances approaching what you would expect for a bolt action rifle. This allows for more cover choices, a higher degree of stealth, and increased survivability in police and combat situations. Furthermore, the extended scope ring rail gives the M16 and AR15 operator more personal choice in selecting a preferred optical configuration which may previously have been unmountable. Manufactured from billet 6061 T6 aluminum alloy and Type III black hard-coat anodized, the GS-1 rail meets MIL-STD-1913. As with the other FIRE System rails, it locks onto the flat top receiver by means of a full length locking side bar and two rounded socket head cap screws. The socket head wrench required for installation is included.