Profile: Greenhill Mfg. Ltd. develops intermittent electronic control systems with the capibilities of drip cool, spray cool and fog / mist cooling. We specialize in economical livestock cooling equipment. Heatstock is a self-regulated heating element that conserves energy. It is made of tough, durable thermoplastic and a heating element. Self regulating heating cable supplies provides enough power to prevent water from freezing. It provides protection against pipe-bursting in the event of power failure.