This four-channel temperature humidity meter which can display indoor & 3 outdoor temperature and humidity simultaneously, is great for home use. It is suitable for desktop placing or wall hanging. Large LCD display, you can easily read the data. Accurate measurement for measuring indoor & outdoor temperature and humidity. Features: Display four-channel indoor & outdoor temperature and humidity at the same time with celsius / Fahrenheit temperature unit for selection. Adopt wireless technology,you can know 3 outdoor temperature and humidity in indoor receiver. Record max/min indoor and outdoor temperature and humidity with temperature trend indication. Alarm function of upper and lower limits of indoor and outdoor temperature and humidity. Can be placed on the table with a bracket or hung on the wall with a hanging hole. With 3 portable transmitter to induce 3 outdoor temperature & humidity and transmit within 100m without obstacle. Temperature humidity meter is powered by 3 * 1.5V AAA batteries or DC 5V, each transmitter is powered by 2 * 1.5V AA batteries.(Not included) Specifications: Material: ABS Color: Silver + White Display: 121 * 106mm LCD Display Indoor Temperature Measuring Range: -10~60 celsius / 14~140 Fahrenheit Outdoor Temperature Range: -50~70 celsius / -58~158 Fahrenheit Temperature Accuracy: +/-1 celsius Indoor Temperature Humidity Detection Period: testing once 30 seconds Outdoor Temperature Humidity Detection Period: testing once 57 seconds Humidity Measuring Range: 20~95%RH  Humidity Accuracy: +/-5%RH Function: Indoor/Outdoor Temperature and Humidity, Max & Min Value Display, Comfort Level Display, celsius / Fahrenheit Switchable, 3 Separated Transmitter Battery of 3 Transmitter: Each 2 * 1.5V AA Batteries(Not Included) Temperature Humidity Meter Power Supply: 3 * 1.5V AAA Batteries or DC 5V (Not Included) Size of Transmitter: 123 * 45 * 25mm / 5.12 * 1.57 * 0.87in Temperature Humidity Meter Size: 169 * 163 * 26mm / 6.7 * 6.4 * 1.0in Transmitter Weight: 56g / 2.0oz Temperature Humidity Meter Weight: 219g / 7.7oz Package Size: 21 * 19.6 * 9cm / 8.3 * 7.7 * 3.5in Package Weight: 590g / 20.8oz Package List: 1 * Temperature & Humidity Meter 3 * Transmitter 1 * User Manual