These popular messenger bags are a Tough cotton canvas. The large main compartment has an integrated divider panel. The large lid Front cover has a Bio-Hazard Logo, also has a metal snap to secure closed. Under that flap is a smaller compartment that boasts "rifle shell" Sleeves, that hold pens rather well. The Shoulder strap is extra Long, there are 4 Steel D rings on the bag so you can carry it as a Shoulder Bag or traditional Back pack. The front pouch is 20 x 22 cm or 8" x 9" and the main bag is 15" x 12" x 8.5" or 38 x 30 x 22cm.