Portable Electric Heater Quick Heating: PTC(Positive Temperature Coefficient) self-regulating heating element produces high heating power that quickly heats up the room and regulates the temperature itself; higher efficiency, durability & safety Advanced Protection: Tip-over safety switch and overheat protection will automatically turn the unit off in the event of it being knocked on its side or overheated. Thermal fuse for extra safety if the overheat protection failed