The PB4SQ from Polaris is an energy-efficient, multistage booster pump that operates quietly & is designed to last. It uses an advanced 5-stage impeller design to deliver greater water pressure for more powerful cleaning. The PB4SQ Booster Pump is spedcifically designed to operate pressure cleaners at optimum efficiency. The Totally Enclosed Fan Cooled (TEFC) motor design allows the pump to run cool & quiet.