The Apple Watch Series 4 kicked off the Apple Special Event at the Steve Jobs Theater today. With a stunning new display that is over 30% larger with curved corners, even in a thinner and slimmer case, viewing maps, photos, and calendar just became easier. The new display comes with a totally redesigned UI that allows more customizable dials, with up to 8 complications that really make the watch pop.

Perhaps the biggest feature of the Series 4 is the on-demand electrocardiogram (ECG). The first over-the-counter ECG product, this FDA-approved app lets you measure and record your heart activity and even save it as a PDF that you can send to your doctor. Just open the app and put your finger on the digital crown for 30 seconds. The Series 4 also screens your heart rate in the background to sense low heart rates and irregular rhythms.

Other features include a totally reengineered digital crown, 50% louder speakers, the same 18-hour battery life, and a gyro-sensor that detects the wearer’s falls, trips, and slips based on watch trajectory. If you’re immobile for 1 minute after the fall, the Apple Watch Series 4 will send an automatic SOS to your emergency contacts.

At $399 for the GPS-only model and $499 for GPS+Cellular, the Apple Watch Series 4 is offered in two sizes, 40mm and 44mm, and comes in three colorways: silver, gold, and space grey. All watch straps from previous generations will be compatible. You can order the Series 4 starting September 14.