Operating Instructions: 1 After drinking , it is recommended to wait 20 minutes before testing, because alcohol takes about 20 minutes into the blood from the digestive organs , and residual alcohol in the mouth takes time to dissipate . 2 To get a more accurate result , the distance should be at least three minutes between each test . 3 Do not use benzene , gasoline and thinners cleaning product ingredients tester . 4 Do not allow any liquid penetrated into the sensor. 5 Operating Instructions: 1 After drinking , it is recommended to wait 20 minutes before testing, because alcohol takes about 20 minutes into the blood from the digestive organs , and residual alcohol in the mouth takes time to dissipate . 2 To get a more accurate result , take a deep breath and give it a hard long blow. The distance should be at least three minutes between each test . 3 Do not use benzene , gasoline and thinners cleaning product ingredients tester . 4 Do not allow any liquid penetrated into the sensor. 5 Reset device by Take Out Batteries then Put them back in and test it again. Package Content 1 Instruction Manual 1 Digital Breathalyzer 5 Replaceable Mouthpieces LCD display testing results recalling Wide measure range:0.00-0.05%BAC or 0.00-0.25mg/l Three LCD display,apart display 0.02%BAC and 0.05%BAC. Sensor: advanced semiconductor oxide alcohol sensor Warm-up time: within 10 seconds Respond time: within 5 seconds Power input: use 2x \"AAA\" alkaline batteries (not included) It has LCD backlight and Key Chain.