The DTG Series of Digital Thermometers allow you to easily monitor your aquarium's water temperature with a large, highly visible LCD displays. The sleek, compact designs provide easy placement, making the DTG-15 and DTG-25 the perfect choice for aquariums of all sizes. The Digital Thermometers are accurate to +/- 2 degrees Fahrenheit. The DTG-15 is fully submersible and has a suction cup mount. The DTG-25 has an adhesive back for easy installation and must be mounted externally.