Nature's Heat Tank Heater Four Paws Economy Heater provides reptiles and small animals the warmth they require to help their digestive system. With Nature's Heat there are no dangerous or obstructive wires in the pet's tank. Available in two sizes Four Paws Economy Heater provides reptiles and small animals the warmth they require to help their digestive system. With Nature's Heat there are no dangerous or obstructive wires in the pet's tank. Available in two sizes