Fast and High-precision Sensor: Adopts professional airway design and high-precision semiconductor sensor. Displays blood alcohol levels quickly and accurately. You can then decide if you want to drink and drive. Easy to use: just insert 2 AAA batteries and turn on the breathalyzer. Wait 10 seconds for the device to warm up, then blow for 3-5 seconds. The results are then displayed on the LCD screen. When the breathalyzer is not in use, it automatically turns off to save energy. batteries not included High Quality Breathalyzer: Uses advanced solid-state alcohol sensor technology to quickly capture breath samples and determine blood alcohol level BAC Automatic warning function: Warning is displayed when the result is between 0.02% and 0.05%, and Danger is displayed when the result is equal to or greater than 0.05%. Wait 20 minutes after drinking for most accurate results