1、One-button operation, automatic shutdown, very convenient to use. Just need three AAA batteries (not included) and you can start operation 2、The operation is simple, press the 1 button to enter preheating (20s), blowing, three modes will be displayed for you, easy to read 3、The test result will be displayed on the LCD screen for about 10 seconds, and the tester will automatically shut down. You can easily change the measurement unit and set the user-defined BAC test threshold. 4、With an advanced sensor, it can respond quickly, with power saving and low voltage indication functions. After the test, it will automatically sleep for 5 seconds 5、With LCD display and audio warning function, the product has a sensitive semiconductor sensor, when the content exceeds the preset limit value, it can easily display the degree of poisoning in the body in a few seconds, and provide the test result (0.01 mg / L ) 1 x Tester20 x Mouthpieces1 x User Manual Item Type: Digital Breath TesterTest Range: 0.000- 0.199% BAC (000-199mg/m)Undervoltage Indication: Vcc < 3.00V± 0.1V displays undervoltage; Vcc < 2.47V± 0.1V undervoltage shutdownAccuracy: ± 0.01%BACOperating Time: Preheating for 100 seconds, response within 5 secondsWorking Environment: -10℃-50℃Display Mode: 3 digits with blue backlight and graphic displayBattery: 3 x AAA alkaline batteries (the machine does not come with batteries)Product Size: Approx. 10.5 x 7.5 x 2.5cm / 4.1 x 3 x 1in