Displays both aquarium water temperature and room temperature in F. Product has four alert features that use both sound and LED Flashes: high temperature alert only (probe), low temperature alert only(probe), both high and low temp alert (Air/Room), both high and low temp alert (probe). Unit has a wide temperature range from -58F to +158F. Included is a heavy duty battery (AAA) with a 2 year life. Instructions: Place probe with suction cup inside aquarium or wet/dry filter. Fully submerge probe under water. Do not submerge meter or allow meter to get wet. To set the four settings slide "Temp/Alert" switchh to "Alert". Then press the "Alert/Select" button to either High Temp, Low Temp, HIgh and Low Air/Room temp, or High and Low probe temp. alert mode. Once the desired temperature is selected press "Alert On/Off" button to activate alert feature. With this feature the alarm will sound and the LED light flashes for 5 seconds every minute when the temperature is above the HIgh or Low set point. Size: 3 1/2" l x 1" w x 4" h Warranty: One year from date of purchase