Progressive Industries Portable Electrical Management Systems (EMS) offer quick and easy RV electrical protection. A true plug-and-play application with no installation required. You will feel secure with multi-mode surge, voltage, polarity, and lost/open neutral protection. Each unit includes a digital display, scrolling continuously through the power source information: voltage(s), current frequency, error code, and previous error code (if applicable). Additionally, the computer is driven by state of the art microprocessors. Over/Under voltage protection Open ground, open neutral and reverse polarity detection and prevention Accidental 240 protection A/C frequency protection Time delay MODEL NO - 0313.1122