i use a military surplus gas mask bag its meant to be worn as a messenger bag and then as a front bag when the gas mask is engaged. i love it its got one main compartment and a few smaller ones for organizing. not only do i use it to carry items i need on the go (like snacks lol) but i also use it for carrying water back to camp and other things like that, its very versatile. it even has a waist strap to keep it from bouncing around ill get a picture up