[Product Information] - A digital alcohol tester (alcohol tester) is a device used to estimate blood alcohol content (BAC), which determines the amount of alcohol in the blood. The test measures the amount of alcohol in the air you exhale.[Use] - The driver first undergoes an alcohol impairment test using a screening device at the roadside. If the test result is positive, an evidential breath test is performed at the police station. If the police suspect that the driver may be driving under the influence of alcohol, or the driver has committed a moving traffic violation, the police can stop the driver at the scene of a road traffic accident and ask him to take a breath test.[How to use] - Turn on the tester and wait 15 seconds for it to warm up, then start the test and the result will be effectively displayed on the LCD screen. You can change the unit (%BAC and mg/l) by pressing the keys[Important] - If the BAC result exceeds certain values, this alcohol tester will emit different tones to notify you so that you can make a better judgment. This alcohol tester is battery-powered. (3 AAA batteries are required - not included in the delivery and must be purchased separately)