Designed for heavy cattle use in extremely cold temperatures. Tested at -20°F for 48 hours without freezing with no animals drinking. Rim design helps keep float balls free of ice buildup. Extra-thick 4 urethane insulation. 30 animal capacity minimum.How they work: Heavy foam insulation keeps water at the perfect temperature, regardless of conditions. Ground water enters the unit between 48F and 56F, where it remains until the waterer is opened by the animal. As the animal drinks, new water enters through the automatic valve and mixes with the water already in the waterer, so it is constantly replenished and prevented from freezing. The water in the waterer is kept in the dark, which prevents algae growth. When the waterer is not in use, an optional Shut-Off Valve Kit prevents water from entering and drains the waterline to prevent freeze up. Energy -Free Waterer float balls push down effortlessly, requiring half the pressure of competitors' float balls, so even calves, sheep and other small animals can drink easily.