Durable polyester construction Sealed on-mat electronics for maximum protection On-mat thermal switch and thermal fuse for redundant safety Insulated design directs heat to the batteries not the enclosure for a 30% reduction in power consumption Piggyback plug standard on 120V models Alpha's battery heater mats are designed with safety and efficiency in mind. Alpha's battery heater mats are a low-cost way of keeping backup batteries operating at their optimal temperature, maintaining battery backup performance at >70% of nominal levels at temperatures below 32°F/0°C. The heater mats' insulated bottoms ensure that energy is directed to the batteries and not wasted heating the enclosure. Their durable polyester outer shells protect the heating elements from damage; their redundant thermal control protection ensures against overheating; and their fused power input protects against shorts. Alpha battery heater mats are a smart addition to any backup power system.