LIFEGARD® Digital Thermometers are used for aquariums, reptiles or greenhouses. All include a long-life AAA battery, plastic probe with suction cup and cord. All models are safe for salt or fresh water use. A large display digital thermometer with Alert feature. Displays both aquarium water temperature and room temperature. Available in °F or °C models. Has four Alert features. (Alarm will sound and LED flashes): High Temp Alert Only (Probe) Both High & Low Temp Alert Only (Air/Room) Low Temp Alert Only (Probe) Both High & Low Temp Alert Only (Probe)