High precision digital breath analyzer: This alcohol tester features a high-precision semiconductor alcohol sensor. It can quickly provide results to determine if you are fit to drive. Test accuracy of 99.1%, with a range of 0.00% – 1.9% BAC / 0.0 – 1.9 g/l. Ideal for drivers. Easy to use: simply insert 2 AAA batteries (not included), turn on the device, wait 10 seconds to warm up, and then blow into it for 3–6 seconds. The result will be displayed on the LCD screen for 10 seconds and then the device will automatically power off. Auto alarm function: If the test result exceeds 0.05% BAC or 0.50% BAC or 0.25mg/L or 50mg/100ml, the device will emit a continuous beep to alert the user not to drive. (Wait 20 minutes after drinking to perform the test for more accurate results.) Lightweight and portable: This alcohol tester can be easily carried in your pocket or wallet. It is perfect for weddings, parties, celebrations, and other social events to help you determine if it is safe to drive.