Durible construction ready when you are to offer continuous clean power. The OutBack GTFX Sreies is a benchmark for others to follow. Sine wave output, intelligent battery charging, modular stackable design, high operating effeciency, weather-resistant sealed chassis, corrosion resistant internal components, field serviceable, integrated network communications, standard 2 year limited warranty. Installation Manual OutBack_gtfx_gvfx_installation.pdf