This universal drain plug de-icer mounts securely into the tank's drain hole to keep the heating element away from livestock. Durable stainless steel heating element is thermostatically controlled and features over-temperature protection for safe, efficient operation. Specially designed plug to fit through all drain holes 3/4-inch diameter or larger. Safe for horses and other livestock, and safe in both plastic and metal tanks. Recommended for tanks 100-300 gallons.