Apple (AAPL) on Wednesday announced a significant update to the Apple Watch sporting significantly larger displays with an FDA-approved EKG feature.

The Apple Watch Series 4 models sport larger screens that display over 30% more than the previous generation, Apple says. Other hardware improvements: the “digital crown,” or turn dial on the watch’s side, has also been improved to include haptic feedback, while the watch’s speaker is now 50% louder. The Apple Watch Series 4 is powered by a new dual-core 64-bit processor to deliver up to twice the performance of last year’s models while maintaining “all-day” battery life.

“Every detail has been thoughtfully considered, and it’s just beautiful,” declared Apple COO Jeff Williams onstage at Apple’s Cupertino, California headquarters.

In addition, Apple also beefed up the Apple Watch’s ability to detect motion and heartbeat, including whether a user falls. The watch can also detect lower heart rates, as well as catch most cases of irregular rapid heartbeats, or “atrial fibrillation.” But perhaps most notably, the Apple Watch now lets users perform an electrocardiogram, or EKG, making the Apple Watch Series 4 the first FDA-approved, over-the-counter EKG consumer device. Performing EKGs can help users detect heart disease. Williams said the EKG features will roll out later this year.

Preorders for Apple Watch Series 4 begin on Friday, with units expected to ship on September 21. Prices start at $399 for the non-cellular aluminum models in space gray, silver and gold, and $499 for the non-cellular stainless steel models in silver, “polished graphite” and gold. Meanwhile, the Apple Watch Series 3 will remain available for sale at $379.

The company also unveiled several new watch faces that take advantage of the larger displays, including images of your loved ones and more fitness information.

Traditionally, Apple has kept quiet on the specific sales figures for the Apple Watch since it first launched more than three years ago. However, Apple CEO Tim Cook referred to Apple Watch sales in 2016 as “off-the-charts” and sales during the 2017 holiday season as record-breaking.

“Apple Watch isn’t just the number one watch world in the world — it’s the number one watch period,” emphasized Cook onstage at Wednesday’s event.

A report from Canalys estimates Apple shipped 3.5 million Apple Watches worldwide during the second quarter of 2018, up 30% during the same period last year. However, Apple’s total share of the smartwatch market dipped, down from 43% to 34% during the first quarter of this year, indicating the smartwatch market overall has become more crowded and competitive.