The back of the thermometer senses the temperature inside the aquarium through the glass… Warning: Thermometer contains glass And small parts. The JBJ floating glass thermometer sticks on the inside of … Brand: TOP FIN, Type: Thermometer, UPC: 737257021600. Keep out Of reach ofchildren. 8 new TOP FIN floating glass thermometer. It’s designed to go outside the aquarium and below the waterline. Directions: Instructions: Proper water temperature is essential To maintain the health And well-being Of your fish. JBJ Floating Glass Thermometer w/ Suction Cup for Aquarium Description Water temperature is a key factor in keeping tank inhabitants healthy. Top Fin® Floating Glass Aquarium Thermometer at PetSmart. FIN 737257021600 Thermometer Specifications You attach it horizontally by using the adhesive. … This thermometer measures 0.75" x 4.25" and weighs a puny 0.3 ounces. Shop all fish heating & lighting accessories online FIN 737257021600 Thermometer Description.