Farm Innovators 3 gal. Plastic Heated Poultry Fountain HPF-100
Product Review (submitted on November 14, 2013):
Has worked fine for me, water hasn't frozen so far down to about 15 degrees F. Only frustration is that you have to keep it pretty level or all the water will syphon out. Have it in my mobile coop, and have to use a board to level it when on uneven ground. Otherwise I've been pleased with its performance.
For what it' worth, both of the previous reviews obviously came from one guy out to discredit the product.