Professional Alcohol Tester:This alcohol tester has a high-precision semiconductor alcohol sensor, provides the most accurate results and alarms when excess alcohol is detected. Test winner with 99.1%, range of 0.00% ~ 1.9% BAC / 0.0 ~ 1.9 g/l. It can quickly provide a result to judge whether you can drive or not. Easy To Operate:Just insert 2 AAA batteries(not included), turn on your Breathalyser. wait for 10 seconds for warming-up, then blow for 3-5 seconds. The result will be displayed later on the LCD screen. The results are displayed for 10 seconds and then automatically switched off. 12 Interchangeable Mouthpieces:This alcohol tester comes with 12 interchangeable mouthpieces. They can be cleaned and recycled, which is good for hygiene. This Alcohol Tester, is CE certified, Ideal for drivers. Automatic Alarm Function:Test result is above 0.05% BAC or 0.50 BAC or 0.25mg/L or 50mg/100ml, the tester will alarm. (Please Notice: Wait 20 minutes after drinking to perform the test, the result will be more accurate.) Lightweight and Portable:Alcohol Tester can be carried anytime and anywhere in your pocket or wallet. It is very suitable for weddings, parties, celebrations and other social events to help you judge whether it is suitable for driving.