The October issue of Popular Science features the BACtrack Vio Smartphone Breathalyzer in their Obsessed column, along with a few other cool tech devices they are currently lusting for. Here's what they say:
"The size of a keychain, the Vio is one of the smallest breathalyzers available. It measures blood alcohol content, and even estimates when the level will drop low enough to safely drive."
Read more on the PopSci site.