Easy to use: Prepare two AA batteries in advance, turn on the power button of the alcohol tester, wait for 15 seconds to warm up, then blow evenly for 3-5 seconds, the result will be displayed on the LCD screen for 5 seconds. (Requires 2 AA batteries - not included) High AccuracyThis breathalyser uses a high-precision semiconductor alcohol sensor to monitor your blood alcohol level to ensure responsible driving. Note: For more accurate test results, please stop drinking alcohol for 20 minutes. When using an alcohol tester, the interval between each test should be 2 to 3 minutes. Sound warning and color difference: After using the alcohol tester, when the test result is lower than 0.08% BAC, the green LED light lights up and emits 3 short beeps; when the test result exceeds 0.08% BAC, the red LED light illuminates and emits 3 long beeps. beep. Measuring range: Alcohol measuring range is 0.00-0.20%BAC. The alcohol test result reaches the maximum value (0.20% BAC), and the value will not increase. Even if the drinking amount increases, the test result still shows 0.20% BAC; Note: In order to obtain more accurate results, please test 3 times every 2-3 minutes to get the average value. What you will get: 1 Breathability Analyzer, 1 Instruction Manual