Borrowed from
www.Sableco.netRail Adapter Systems (RAS) for AR-15 and CAR-15 Rifles.
The RAS consists of four parallel Military Standard M1913 rails. One each above, below, and along the sides of the barrel. They allow the user to mount a variety of useful accessories such as reflex sights, lasers, forward pistol grips, flashlights, bipods, etc.
#98064 M4 RAS Forend. Fits Carbines with M-4 and Hbar 16" barrels with standard Carbine length handguards. Comes with three 11-Rib Panels. $275.00