The Lapp Drinkers are energy free, they need no gas or electric.  Keeps cold out to approx. 20 below.  Great for small livestock as well as large.  Keeps water cooler in summer.  Round corners-better for animal durability and safety.  Will work with gravity flow or under pressure.  Very well insulated with high density urethane foam. Comes in single model shown in pictures and in a double model to use on fence line for two pastures or paddocks. Call 918-267-4307 or 918-633-7353  for pricing and to place an order.