The Responder IV is our largest and most technically organized ambulance response bag. It is very similar to the Responder III in the way that it opens and carries.The main compartment is sized to work with any of our modular kits, but is long enough to fit an O-2 bottle, and will accept our O-2 Caddy insert. The Responder IV also sports twin side pockets (long enough to fit stiffneck type collars) and two end pockets. All pockets and top lid are built with velcro compatible fabric, and can be completely organized using any of our M.O.S. units. There are fluid proof handles on each end of the bag, padded bottom, giant #10 coil tape reinforced zippers, and of course our super tough SI-TEX.