Usage Tips:Is Smart Device : NoUsage : HouseholdDisplay Size : 1.9 Inches & UnderOrigin : Mainland ChinaCertification : CEBrand for Hygrometer Thermometer : INKBIRD Digital Hygrometer Indoor ThermometerModel for Hygrometer Thermometer : ITH-20R Digital Hygrometer Indoor ThermometerTransmission Frequency : 433MHzTransmission Distance : about 300 FeetMaximum Available Transmitters : 3 outdoor transmittersPower Supply : 2 AAA BatteriesDisplay Type : LCD ScreenReceiver Size : 75*64*21mmTransmitter Size : 75*64*21mmTemperature Range of the Receiver : -20~60 (-4~140F)Humidity Range of the Receiver : 10~95%Temperature Range of the Transmitter : -40~70 (-40~158F)Humidity Range of the Transmitter : 10~95%Temperature Range of the Outdoor Probe : -50~125 (-58~257F)Temperature Accuracy : 1Humidity Accuracy : 5%Sampling Time : 10 SecondsEasy Operation : come with ansembled item, install the battery and use right awayExternal Probe : can use it in a pool or in a brewhouseWarranty Policy : 12 months for ITH-20R Digital Hygrometer Indoor Thermometer