High precision digital breathalyzer: This alcohol tester features a high-precision semiconductor alcohol sensor that quickly delivers results to help determine if it is safe to drive. Accurate test results with a detection range of 0.00% to 1.9% BAC or 0.0 to 1.9 g/L. Ideal for personal use by drivers. Easy to use: Simply insert two AAA batteries (not included), turn on the device, and allow 10 seconds for warm-up. Blow steadily into the mouthpiece for 3 to 6 seconds. Results appear on the LCD screen within seconds and are displayed for 10 seconds before the device automatically powers off. Auto alarm function: If the test result exceeds 0.05% BAC, 0.25 mg/L, or 50 mg/100ml, the device emits a continuous ble 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 storage in a pocket, bag, or wallet. Suitable for use at social events such as parties, weddings, and celebrations to help assess fitness to drive.