Need to drive or operate heavy machinery? BACtrack, a company specializing in breathalyzers, wants to make sure you know when you’ve hit your limit. Introduced at CES and shipping later this year, the BACtrack Skyn is a strap that attaches to your Apple Watch band and provides real-time feedback of your blood alcohol content. Users can monitor the loss of their sobriety on demand, or configure the device to vibrate when you’re nearing the legal limit, allowing you to gracefully pass on that third glass of Champagne without causing a scene. BACtrack also hopes that the device’s real-time monitoring capabilities will present new opportunities for the research and treatment of alcoholism.