Cast aluminum with non-stick coating to reduce corrosion and eliminate lime buildup. Thermostatically controlled. Keeps water from freezing down to sub-zero temperatures. Submersible and designed for multiple uses: birdbaths, buckets, small animal waterers of 15-gallons or less. 150 watts. Dimensions: 7.5" x 4.75" x 1" plus long 5.5-foot power cord. By Songbird Essentials.