Before you buy a heater, please consider whether you are going to use your heater in an area that is shielded from rain, snow and sunlight or if it's going to be exposed to the environment. Sunlight and extreme temperatures can cause the plastic on standard electrical cords to degrade over time. Once the wire is exposed, it's a safety hazard. Likewise, rain can get into the interior of certain heaters and come into contact with electrical components and create the same safety hazards. For example, "Pie Pan" style heaters like the one Sue Gremlin posted above are only intended to be used indoors. They also need to be used with a galvanized waterer, not a plastic one. Check the manufacturers instructions carefully. The last thing you want is to create a safety hazard. Please be safe!