Mega BAck pak empty.This is an extremely large backpack/trauma bag made of Cordura® nylon. The main compartment measures 20" H x 15" W x 7" D, is padded with closed cell foam, and has a #10 YKK heavy duty self repairing nylon zipper.This bag has 16 pockets and compartments. On the outside back is a 15"x8" gussett pocket and a 15"x10"x3" zippered pocket. The two side pockets and top pocket each measure 15"x5"x21/2".