SMART AUDIBLE ALARM ALCOHOL BREATHALYSER:Test Range:0.00-0.19% BAC (or 0.0-1.9g/l). When your test result is equal to or greater than 0.05% BACor 0.5g/l), the "Danger" symbol will be displayed in the LCD display with beep audible alert. When your test result is between 0.02% BAC (or 0.2g/l) and 0.05% BAC (or 0.5g/l), It only displays the "Caution" symbol without beep alarm alert. ACCURATE EASY TO OPERATE: Pressing the power button for 1-2 seconds to start the device, wait for 10 seconds for warming-up, then blow for 3-5 seconds, the test result will be displayed on the LCD screen, which is designed with orange backlight, easy to read. Quick response and accurate result. DURABLE ENERGY SAVING: Using 2 x AAA alkaline batteries (not included), after the result being displayed for about 10 seconds, the "OFF" symbol will appear for 2-3 seconds and the alcohol tester be turned off. COMPACT PORTABLE: The alcohol test breathalyzer with key chain is small and lightweight., it's small and easily fits in a purse or pocket, hung on a keychain, or placed in a car. 5pcs mouthpieces, perfect for you and your family to make alcohol testings, giving you and your family professional accuracy for safe driving. WARM TIPS: After drinking , it is recommended to wait 20 minutes before testing, because alcohol takes about 20 minutes into the blood from the digestive organs , and residual alcohol in the mouth takes time to dissipate. To get a more accurate result , please wait three minutes between each test .