Product parameters: Indoor temperature range: -4F - 158F (-20C - 70C) Outdoor temperature range: -40F - 158F (-40C-70C) Humidity range: 20%-95% Temperature display unit: C/F optional (default is C) Temperature Resolution: 0.1C/F Humidity Resolution: 1% Refresh rate: 10 seconds. Error: temperature plus or minus 1 humidity plus or minus 5% Wireless reception range: 100 meters RF Radio Frequency: 433 MHz Function: time function, 1 set of alarm clock, snooze function, backlight function (backlight duration 30 seconds) Indoor unit: 3 AA batteries (battery not included) Transmitter: 2 AA batteries (battery not included) Host size: 95*26*112MM Transmitter size: 53*25*112MM Host display size: 4 inches Host net weight: 142g Transmitter net weight: 55g One-to-one packaging details: Single set of product packaging size: 155*33*135MM Single set of product packaging weight: 245g One-to-three packaging details: Single set of product packaging size: 13.5*6*13.5CM Single set of product packaging weight: 367g Specifications: Product Features: 1. Measure indoor and outdoor temperature and humidity, convert Celsius and Fahrenheit 2. Maximum and minimum temperature and humidity memory function 3. View historical temperature and humidity data 4. Up to 3 outdoor units can be connected (with one transmitter, choose one-to-one order, with three transmitters, choose one-to-three to order) 5. Two high magnetic magnets on the back shell of the main unit, which can be adsorbed on metal objects 6. There is a bracket on the back of the host, which can stand in a horizontal position 7. High sensitivity touch button control, easy to operate 8. Time, alarm clock, snooze function 9. Temperature and humi