It's a twin diaphragm pump with an air shuttle valve. Air pressure forces one diaphragm to pump while the other draws in liquid, and at the end of the piston range the shuttle valve switches it to the other diaphragm. There's a small drop in pressure as it switches but it's not noticeable on a system like foam brush. Hook up is as simple as mounting the pump (It must be mounted vertical) and connecting the inlet, outlet and air supply. All that mess of your current pump, bladder tank and pressure switch control can be removed completely.