The breathalyser uses a high precision semiconductor alcohol sensor.Blow for 5 seconds and your BAC results are displayed 10 seconds later on a bright, easy to read LCD screen.for more accurate results, take the average value after 3 consecutivetests. This portable alcohol tester is equipped with a sensitive semiconductor sensor, This alcohol tester is used to measure the alcohol concentration in the human body. All test results are displayed on the LCD display, which helps you clearly see the readings, including the battery level, and issues an alarm when the battery level is low. there is an automatic shutdown function. When the breathalyzer is turned on, if it is not operated for 20s, it will automatically shut down to save power. For more accurate test results, please stop drinking alcohol for 20 minutes Using the alcohol tester, the interval between each test should be maintained for 2 to 3 minutes. Product features: 1. Digital display of alcohol concentration results with prompt sound 2. Quick response and recovery 3. Alarm points can be 4. Red light backlight 5. Automatic shutdown power saving function 6. The mouthpiece is replaceable, and 5 mouthpieces are delivered. Technical Parameters: Sensor: Semiconductor alcohol sensor Warm-up time: within 10 seconds Response time: within 5 seconds Test range: 0.00%-0.19% BAC & 0.0-1.9 g/L Power supply: Use 2 "AAA" alkaline batteries (not included with this machine) Regardless of whether the product is used or not, manufacturers and sellers will not bear any responsibility for illegal activities. For example: drunk driving, working at heights. Everyone reacts differently to alcohol, so the test results are for reference only and cannot be used as a criterion for determining the results. Material: plastic colour: Black Package Contents: 1 x Alcohol Tester 5 x mouthpieces Only the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.