NEW SmartTemp Thermometer. This unique design combines a thermometer with a magnet. The Thermometer goes on the inside of the tank and the magnet goes on the outside to hold the SmartTemp firmly in place, no suction cups needed! The SmartTemp also offers a Green Safe Zone which indicates the optimal temperature range. A High-End Accuracy- (+/-) 1.5 F and the SmartTemp has large easy to read numbers.