The U.S. Food and Drug Administration (FDA) cleared the very first medical device for the Apple Watch. The approved device is a sensor that detects irregular heartbeats, which tucks into the wristband.

Known as the KardiBand, AliveCor’s device is based on personal electrocardiogram (EKG) technology. When combined with the Apple Watch and the Kardia companion app, the wearable is ready for action.

All users have to do is place their thumb on the wristband sensor for 30 seconds, located just below the watch face. The app then immediately displays the results. Users will either get a clean bill of health, or receive a notification of an irregularity, such as atrial fibrillation (AFib).

AliveCor has also announced a new feature in its Kardia app called SmartRhythm. Mixing AI, heart rate, and movement data, the feature offers a continuous evaluation between heart and physical activity. If the two are out of concert, the device will prompt for an EKG reading.

“KardiaBand paired with SmartRhythm technology will be life-changing for people who are serious about heart health,” says AliveCor CEO Vic Gundotra. “These capabilities will allow people to easily and discreetly check their heart rhythms when they may be abnormal, capturing essential information to help doctors identify the issue and inform a clear path of care to help manage AFib, a leading cause of stroke, and other serious conditions.”

KardiaBand is currently available for $199, however, users must also have an AliveCor Premium subscription, costing $99 a year.

To learn more, watch the KardiaBand demo video below.