High precision digital breath analyzer: This alcohol tester features a high-precision semiconductor alcohol sensor that quickly provides results to help determine fitness to drive. Accurate test performance with a detection range of 0.00% - 1.9% BAC or 0.0 - 1.9 g/L. Ideal for personal use by drivers. Easy to use: Simply insert 2 AAA batteries (not included), power on the device, and allow 10 seconds for warm-up. Blow steadily into the mouthpiece for 3–6 seconds. Results are displayed on the LCD screen within seconds, remain visible for 10 seconds, then the device automatically powers off. Auto alarm function: If the result exceeds 0.05% BAC, the device emits a continuous audible alert to warn the user against driving. For more accurate results, wait at least 20 minutes after consuming alcohol before testing. Lightweight and portable: The compact design allows easy carrying in a pocket or bag. Suitable for use at weddings, parties, celebrations, and other social events to assist in making responsible decisions about driving.