Pure sine-wave inverters produce in many cases cleaner electricity than normal utility power from your local electric company and should be used when operating AC motors for long durations such as: pumps, refrigerators compressors etc... Invertek inverters supply pure sine wave AC output power and are housed in an aluminum chassis for harsh climates. The LED meter displays battery voltage and output watts. The 300 to 1500 watt models are transformer based and the 2500 watt is solid state. These inverters are switch selectable between 50Hz/60Hz and provide overload protection. Built-in RS232 interface for remote control and transfer switch except on the 300 W model.