Coralife - Digital Thermometer
The Coralife Digital Thermometer features an easy to read digital display with temperature in either Fahrenheit or Celsius. It attaches to the aquarium via a small suction cup. The cord for the temperature probe is 3 feet long and the battery for operation is included.
Rivers to Reef says: This is probably the best thermometer that combines accuracy and read speed at a reasonable price. For a clean look the probe can easily be hidden in your display tank or used in the sump.