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 testing with a range of 0.00% - 1.9% BAC or 0.0 - 1.9 g/L. Ideal for personal use by drivers. Easy to operate: Insert two AAA batteries (not included), power on the device, allow 10 seconds for warm-up, then blow steadily for 3 to 6 seconds. Results appear on the LCD screen and remain visible for 10 seconds before the unit automatically powers off. Auto alarm function: If the result exceeds 0.05% BAC, 0.50 g/L, 0.25 mg/L, or 50 mg/100 mL, the device emits a continuous audible alert to warn the user against driving. For best results, wait at least 20 minutes after drinking before testing. Lightweight and portable design allows convenient carry in a pocket or bag. Suitable for use at weddings, parties, celebrations, and other social events to assist in making responsible decisions about driving.