New products on the market are helping people monitor their blood alcohol levels. Some devices link to a smartphone, NPR reports.

One device, called the Vio, is a key chain alcohol test about the size of a lighter. It sells for $50. A person blows in the device, which then determines whether their blood alcohol concentration (BAC) is around or over the legal limit for driving.

Keith Nothacker, the CEO of BACtrack, which makes Vio, told NPR the device might help reduce drunk driving rates. “Previously there was a stigma with alcohol testing, and we’ve been fighting that stigma,” he said. “We want people to talk about their BAC and not be embarrassed.”

Another device, the Breathometer, plugs into the audio jack of a smartphone, and connects with an app. It also sells for about $50. Both the Vio and Breathometer can help a person determine how long it will take them to reduce their BAC back down to 0. “So if you’re drinking late, you’ll see that you won’t sober up until the next day in a lot of cases,” Nothacker said.

The devices are not as accurate as those used by police, the article notes. But they can still be useful in helping people decide they shouldn’t be driving, said Michael McDonell, Associate Professor in the Department of Psychiatry and Behavioral Sciences at the University of Washington. “In study after study, we see that just objectively tracking your use of [a substance] will reduce your use,” he says.

McDonell added, “If the outcome is to help a person stop using or reduce their use of alcohol, accuracy is less important. And those expensive devices are never going to get out there to everybody.”