Product Read More Press And Hold C/F Button For 2 Seconds To Enter Temperature Calibration Mode. Then Use The ""+"" Or ""-"" Buttons To Adjust The Temperature To The Desired Value. Then Press C/F Button Again To Confirm, Then Enter Humidity Calibration Mode. In Humidity Calibration Mode, The Display First Flashes And Displays 0% (Default). Press The ""+"" Or - Button To Adjust The Humidity To The Desired Value. After The Humidity Calibration Is Completed, Press C / F Key Again To Confirm And Exit The Calibration Mode For Details, See The Manual Temperature Measurement Range:-10C~50C (14 ~122F) Measurement Accuracy For Temperature:1C(2F) / Resolution For Temperature: 0.1C (0.1F) Humidity Measurement Range: 20%~95% Measurement Accuracy For Humidity:5% (Range 30%-90%) / Humidity Resolution: 1% Note This Product Is Suitable For Indoor Use, Please Do Not Place It Outdoors Do Not Put In The Refrigerator, Extreme Low Or Extreme High Temperature Is Not Suitable For This Measurement Product Do Not Place Near Water, The Humidity Measured At The Edge Of The Water Is Too High When The Value Is Unclear And The Number Beats, Maybe The Battery Is Dead. Please Replace The Battery As Soon As Possible Specifications Product Weight: 133G Battery: Aaa Batteries, 2 Pcs (Not Included) Backlight: With Orange Backlight Measurement Period: 10 Seconds Temperature Range Available For Manual Calibration: -0.5C~0.5C Available Humidity Range For Manual Calibration: -5%~5% Package Included 1X Temperature Hygrometer (Product Weight: 133G) 1X Manual (The Product Don'T Include The Battery, Please Buy 2 Aaa Batteries By Yourself)