The Accuracy International SR chassis has quite a few interesting features that set it apart from others. The forend tube has an integrated RRS dovetail along with a portion of the chassis just forward of the magazine well. There are two barricade stops forward of the magazine. This allows for forward pressure when you are shooing off of any type of barrier. Keyslot is used for attaching AI accessories. Keyslot locks into conical cutouts on the backside of the forend tube making for a rock solid lockup. The AI SR Chassis comes with one Accuracy International AX AICS .308 Magazine (5 Round).