Today at a special event at Apple’s headquarters, Apple’s COO Jeff Williams unveiled the next generation Apple Watch. It’s thinner, faster and has a larger screen than previous generations. But that’s to be expected. The Apple Watch Series 4 is packed with several features that use the built-in heart monitor for medical purposes.

The Apple Watch has always included a built-in heart rate monitor but it has been limited to basic, standard functions of tracking the wearer’s heart rate.

The watch can now perform an ECG, detect atrial fibrillation, and detect when a person’s heart rate is too low. Apple even got the Watch cleared by the FDA for direct-to-consumer purchase, a first over-the-counter offering for ECG-enabled devices, Williams said.

Note, however, this is not the first ECG-enabled device to receive FDA clearance. Late last year, the FDA cleared AliveCor’s Kardiaband device made for the Apple Watch for over-the-counter purchase and just this week AliveCor announced it had received FDA clearance to detect high potassium levels in the blood using its Kardiaband device.

Regardless, an integration directly into the Watch seems easier to use. According to Williams, who gave a demo on stage at the event, a person just needs to open the app, touch a finger to the digital crown, and the Watch performs the test using the electrodes built into the back of the watch. Because a person’s finger is touching the crown, the watch can detect electrical impulses from the heart and process the pulses with an algorithm built into the watch.

The entire process takes just 30 seconds.

Several companies and researchers have been using previous versions of the Apple Watch to detect AFib. The form factor and technical specs of the Apple Watch makes it a great device for such a test. But until now, the ability to detect AFib has been limited to these tests. Apple will soon make it available to all wearers of the Apple Watch 4.

All the health data is encrypted on the device and in the cloud, Williams said. AFib detection and ECG will be available later this year in the U.S. The company will then roll them out to other countries around the world.

The Series 4 starts at $399 for the aluminum version, and $499 for the aluminum version with cellular features. Pre-orders start on Friday and the device will be available on September 21st.