Medical device company based in San Francisco, BACtrack, has won a $200,000 grand prize last week at the Wearable Biosensor Challenge sponsored by The National Institute of Alcohol Abuse and Alcoholism (NIAAA).

The purpose of the competition was to, “design a discreet device capable of measuring blood alcohol levels in near real-time,” in an effort to improve on existing alcohol biosensor technology, according to the NIAAA. The agency received eight submissions after announcing the challenge in March 2015. 

Each submission was judged based on a variety of factors like accuracy and reliability as well as its data collection and storage capabilities. Most of the products came in the form of wearables that gaged blood alcohol content through perspiration, but one notable outlier was a color-changing tattoo.

BACtrack’s winning entry was a prototype dubbed BACtrack Skyn. It’s a wristband monitor that monitors the wearer’s blood alcohol levels through sweat. The device, though, won’t be able to provide real-time information. It measures ethanol seeping through a person’s skin, which is a process that can take 45 minutes, explained The Verge.

The device is still a prototype, but the lack of offering real-time information could hinder initial early adoption by law enforcement and medical professionals, because it’s not intended to be a replacement for current breathalyzers.

However, the head of NIAAA George Koob, Ph.D., told Reuters he expects the wristband to become a valuable tool for the alcohol research community.

“It can help doctors accurately measure a patient’s drinking history, and not just depend on the most recent tests,” he told the publication adding it could help a lot with treatment.

Reuters added that BACtrack has not submitted its invention to the Food and Drug Administration for marketing approval, but the firm’s site has started accepting requests for pre-orders that will be shipped in “limited quantities” at the end of the year.

Watch a brief clip of the BACtrack Skyn in action below.