SD-04 Rooftop mounted bus air conditioner is designed for 8-9.3 meter city bus or 8-9.5 meter coach, the compressor is powered by vehicle engine, and the control system is powered by vehicle alternator. ---------- Click to see it details here: www.guchen.com/bus-air-conditioner/sdd-04.html --------- If interested, please mail to info@guchen.com