Use this to hold your car keys and you will never risk driving home again with alcohol in your system. Uses a unique "traffic light" display to tell if you are completely safe to drive, borderline, or if you should leave the driving to someone else. Easy to use, and even has a timer that you can set if you would like to take some time out before checking again. Could save your licence, or even a life ! Never risk drinking and driving, and always carry your own personal breathalyzer.