With a self-priming CMB-SP PM booster set, you can start to improve your water pressure in an instant. Consisting of just a Grundfos multi-stage, centrifugal pump and a Grundfos PM1 or PM2 pressure manager, the CMB-SP PM is an extremely compact unit. Thanks to the automatic pressure manager which starts and stops the pump according to demand, it can deliver optimal water pressure where and when it is needed.