New iPhones weren't all Apple had to show off in California today, because it also took the wraps off the Apple Watch Series 4. The new smartwatch brings with it an edge-to-edge display, a faster processor, and advanced heart rate monitoring that can even give users an ECG reading.

That ECG (electrocardiogram) function is perhaps the biggest news – the FDA-approved upgrade can monitor heart rate and electrical activity in a way that would previously have required a visit to the clinic, or at least an Apple Watch accessory.

While it's not a guaranteed way of detected heart irregularities like atrial fibrillation, Apple says, it can flag up potential problems that you can then report to your doctor. The feature is going to be enabled in the US later this year.

The Apple Watch Series 4 can also detect an abnormally low heart rate and signs of atrial fibrillation through the improved sensors on the back of the device, too.

On top of that, the smartwatch can now detect falls through some smart sensing and an improved gyroscope and accelerometer – these sensors are now more accurate and can take readings faster. If you take a tumble, you'll be asked if you need help; if you don't respond and stay inactive, the watch can even call the emergency services and your emergency contacts for you.

Elsewhere, the Apple Watch Series 4 borrows a trick from the iPhone X, with an edge-to-edge display and curved corners that virtually banish the bezels. Overall the screen is 30 percent larger than it was with the Apple Watch Series 3. The two sizes have been upped from 38 mm and 42 mm to 40 mm and 44 mm, though because of the screen improvements, the watch isn't actually any bigger.

The user interface has been redesigned to take advantage of the new display, with more room for complications. Apple has taken the time to design new watch faces and new complications too, and there's also a relaxing set of three watch faces to go alongside the Breathe app.

To improve calls, Apple has made the speaker 50 percent louder and moved the microphone to the other side of the watch. Cellular reception is also improved through the black ceramic and sapphire crystal materials used on the back, Apple says.

Meanwhile the digital crown now has haptic feedback to more easily work out what you're selecting. It's also how the ECG measurements are taken.

Everything should be faster too, thanks to a 4th-generation S4 chipset specially designed by Apple – it's apparently up to 2x faster, though Apple didn't say what it was two times faster than. The Watch Series 3? A 2007 iPhone?

There are a bunch of improvements here, though the watch might look more or less the same on the surface, and watchOS 5 will bring even more (like dedicated modes for yoga and hiking). Despite all the upgrades, Apple says you can still expect the same 18-hour "all day" battery life as the Series 3 had.

You can pick up the new Apple Watch Series 4 in silver, gold, or space gray; pre-orders open on Friday September 14, with shipping a week later on September 21. For the smallest 40 mm size, you'll pay US$399 for the basic model and $499 for the model with cellular calling capabilities, and for the 44 mm versions that goes up to $429 and $529.

Product page: Apple

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