Usage Tips:12 Interchangeable Mouthpieces Breathalyzer comes with 12 pieces of mouthpieces, the mouthpieces can be cleaned and recycled. Super compact design, breathalyzer fits in your pocket and is easy to hold and carry wherever you go. Ideal for drivers. Police Accurate BreathalyzersThe breathalyzer with professional airway design and high-precision semiconductor sensor, test your blood alcohol concentration (BAC) more accurately and faster. Test winner with 99.1%, range of 0.00%~1.9% BAC / 0.0~1.9g/L. Alarm FunctionTest result above 0.05% BAC or 0.50 BAC or 0.25mg/L or 50mg/100ml, Breathalyzer emits a continuous beep and To remind drivers not to drive. With backlight, easy to read. Easy to UseJust insert 2 AAA batteries, turn on your breathalyzer(not included). wait 20 seconds to warm up, then you can start testing. The breathalyzer will turn off automatically to save power when no operation. Package Contents1* Breathalyzer, 12* Mouthpieces, User Manual.