High precision digital breath analyzer: This alcohol tester features a high-precision semiconductor alcohol sensor that quickly provides results to help determine if it is safe to drive. Accurate testing with a range of 0.00% - 1.9% BAC / 0.0 - 1.9 g/L. Ideal for personal use by drivers. Easy to use: simply insert 2 AAA batteries (not included), turn on the device, wait 10 seconds for warm-up, then blow steadily for 3-6 seconds. Results are displayed on the LCD screen for 10 seconds before the device automatically powers off. Auto alarm function: if the result exceeds 0.05% BAC or 0.25 mg/L, the device emits a continuous beep to alert the user. For best results, wait at least 20 minutes after drinking before testing. Lightweight and portable design allows the device to be carried easily in a pocket or bag. Suitable for use at weddings, parties, celebrations, and other social events to assist in making responsible decisions about driving.