This system approach simplifies the complete installation. Package includes: Pump Plus HO and 12V Auto Pump_12V, 100 PSI Max, air compressor Auto Pump, see pg. 43 for specs and pg. 47 for optional accessories_11A charger Model Pump Plus HO for charging a dual battery bank. Automatic operation regulates the output to dual battery banks. A patented built-in sense circuit checks the battery voltage 120 times per second to compensate for a voltage drop in charging wires providing a quick re-charge without overcharging. LED Display optional. Air Compressor power mode selector switch_DC Powered full time from the vehicle�s battery_AC Powered only from the battery when the vehicle is plugged into the shore line _Automatically shuts off the compressor when disconnected from the shore line, taking the 12A load off the vehicle�s battery