The main compartment is 20''H X 12''W X 7.5''D, with 3 internal mesh pockets. With lockable metal zippers. 4 each - side compression straps with quick connect buckles. The top front zippered compartment 13''H X 11.5''W X 3''D with several internal pockets to organize your gear, with lockable metal zippers.The top outside vertically zippered expandable pocket measures 12.5''H X 11.5''W with six rows of MOLLE webbing and loop fastener patch area for name tape or patch. The bottom front zippered compartment 12''W X 5.5''H X 2.75'' with several mesh pockets and has two rows of MOLLE webbing on the outside. Side zippered pockets 9''H X 5''W X 2''D on each side of the backpack with MOLLE webbing.