High precision digital breath analyzer: This alcohol tester features a high-precision semiconductor alcohol sensor that quickly delivers 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: 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 display on the LCD screen within seconds and remain visible for 10 seconds before the unit automatically powers off. Auto alarm function: If the test result exceeds 0.05% BAC, 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 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.