This EcoPlus 716555 thermometer and hygrometer is a great tool for your grow project. This thermometer not only measures temperature, but humidity as well, and is enclosed in a waterproof casing, which is also chemical and UV resistant. This unit has a large screen digital readout and displays temperatures in Fahrenheit and Celsius degree measurements. The battery operated thermometer features a wireless remote sensor, which transmits up to 50 feet and is also expandable to accept 2 additional sensors, giving you complete control over your grow project. Uses 2 AA batteries which are included.