TMC-36501 4 chamber diaphragm design with a smooth constant flow. Can serve up to 3 to 4 outlets. Built in check valve to prevent back flow. Snap in inlet and outlet fittings ½" bsp and 13mm hose tails included. Built in thermal overload protection. Self priming and can be run dry. 1.4 bar cut in pressure and 2.8 bar cut off pressure. These are fixed and cannot be altered.