[High Accuracy and Fast Sensor] The alcohol tester features a professional airway design and high-precision semiconductor sensor for quick and accurate display of blood alcohol content. This helps users make informed decisions regarding alcohol consumption and driving. [Easy to Use] Insert three 1.5V AAA batteries, attach the mouthpiece, press the start button to begin the countdown. After a 10-second preheat, breathe into the device steadily five times within 10 seconds. The blue backlight LCD screen displays the test results directly. Press the power button to switch between measurement units. [Auto Alarm Function and Power Saving Mode] Offers three selectable measurement units: % BAC, BAC, and mg/L. If the result exceeds 0.5 BAC, an audible alarm sounds as a warning. The device automatically powers off after a period of inactivity to conserve battery life. [Compact and Portable Design] This mini alcohol analyzer is small and lightweight, easily fitting in a car, handbag, backpack, or briefcase. Includes a carrying case that securely holds the breathalyzer and mouthpieces for convenient transport. Batteries not included. Note: Measurements are taken manually; please allow 13 cm variation. Due to differences in lighting and screen settings, slight color variations may occur. Actual product may vary slightly from images shown.