This is a genuine US military surplus Demolition Equipment Bag in Olive Drab green. This is a rare find, and even more rare that they are still brand new in the original packaging!
You could use these bags for any number of things, they feature a sling style carrying strap, two cinch buckle closure straps on the main flap, and 4 ties (one in each corner). On the inside of the bag is one large main compartment, with a smaller compartment/sleeve on the front. The bag is closed by a flap lid that has two hook and loop fasteners as well as two cinch buckles.