Easy To OperateThe portable breathalyzer is extremely convenient and easy to use. Just insert 3 AAA batteries (not included), turn on the breathalyzer, wait 10 seconds for it to warm up, and then blow the exact results on the screen for 5 seconds into the tester. Automatic alarm This breathalyzer has a large LCD screen with blue backlight.the buzzer will automatically alarm when the alcohol content is exceeded. Perfect Gift We Offer 20 mouthpieces , Alcohol Analyser is small and lightweight,Which is perfect for testing yourself as well as your friends and family. Please NoticeAfter drinking, it is recommended to wait 20 minutes before testing,To get a more accurate result , please wait three minutes between each test.This Alcohol Tester, is CE certified. 100% Best ServiceIf you have any problem about our breathalyzer ,please be free to contact us we will try our best to meet your requirement.