The Mars spd is designed to protect your HVAC equipment for power surges, spikes and transients. Power surges can damage compressors, controls, sensors, logic boards and ecm motor electronics resulting in costly repairs. The Mars surge utilizes state-of-the-art thermally protected mov (tpmov) technology to outperform competitive units while providing safe and reliable protection. Mars spd is designed to protect the entire HVAC unit and controls: compressors, heat pumps, ecm Motors, control boards and sensors.