Safely maintains open water to 20 degrees below zero Fahrenheit. Natural color and 18 inch long cord blend in with nearly every birdbath. Virtually indestructible. May be spray painted any color to match any birdbath. Will not calcify, rust, or leave stains in birdbaths. Won't burn or melt plastic birdbaths. Available in 80 watts for even the largest of bird baths. MET listed. Durable enamel finish is easy to clean. Thermostatically control. Includes 3 year Warranty from Manufacturer.