Breathalyzer maker BACtrack on Tuesday announced the BACtrack Vio, a $49.99 alcohol testing unit that fits on a keychain and feeds the results over Bluetooth to your iPhone or Android smartphone. BACtrack has been making breathalyzers for years, but it didn’t release its first smartphone unit until last year. The new Vio is more compact and affordable than the original BACtrack Mobile. Alongside the product launch, BACtrack has also released an improved app with a better-looking design and new features like the ability to guess your blood alcohol content ahead of time. The Vio is a bit thicker than a large USB stick, but it’s not too big for your pocket. The device is powered by a AAA battery, which I prefer over the rechargeable micro-USB batteries that some units have. To test your levels, open up the app on your phone, hold down the button to pair the Vio and then wait for the device to warm up.