The M240 Egress kit is basically a gun case for the M240 Gun and accessories.

The M240 Egress Kit is an emergency parts bag, usually kept on a helicopter. In the event of a crash, the crew chiefs can grab the kits, and dismount the M240C guns, and "egress" or escape, the crashed helicopter, and use the parts in the kit to remove the spade grips and bottom plate on the M240C, and convert it to a M240B, with a pistol grip and stock, which is the Infantry/dismounted configuration, so they can defend the crash site, until help arrives. 

The Egress Kit bag / case is approximately 31" long and is perfect to carry a SBR or SBS in as well as some carbine pistols or Drako's.