The Liberty Pumps PC237-411 is a fully assembled pump combination that features a primary 115-Volt sump pump and the model 441 battery back-up pump. The primary sump pump (Model 237) is a lightweight, high performance submersible pump with aluminum housing for superior motor cooling. Quick-disconnect 10 ft. standard power cord allows replacement of cord in seconds without breaking seals to motor. Liberty's model 441 battery back-up pump takes over when the power goes out. Operating from the power of a 12-Volt deep cycle battery (sold separately), the 441 features an efficient 12-Volt pump, advance 3-stage charger with switch mode technology and easy wiring with slip connectors. Batteries sold separately.