If you want to make sure you don't get behind the wheel impaired, all you need is your phone.
The Breathometer is a new gadget that plugs into the iPhone 4 or 5 or any Android device running version 4 or higher, using the audio jack. All you need to do is start the app, blow into the sensor and your screen will tell you if someone else needs to drive. As an added bonus, the Breathometer can easily be attached to your keys.
