- Read our Apple Watch 4 review
Other hardware changes include a speaker that's 50 percent louder, and a re-engineered digital crown that builds in haptic feedback. There's a new S4 64-bit dual-core processor that's two times faster, while the black ceramic and sapphire crystal rear improves cellular reception.
Apple has also redesigned the WatchOS software, and there are now eight complications. You can customise these with the things that are important to you, such as health and fitness data and different time zones.
Some of the more interesting new features are to do with health, however. The Apple Watch Series 4 is the first consumer product offered over the counter to allow ECG (electrocardiogram) tests wherever you are, important for helping to diagnose certain heart diseases. (This feature will not be available at launch.)
The Series 4 can also send notifications if your heart rate is too low, or if you have an irregular heart beat. And it can detect a fall - should you be immobile for a minute it will automatically trigger an emergency call and send a text with your location.
Despite all these changes, Apple Watch Series 4 has the same 18-hour battery life as previously.
Apple Watch Series 4 price and release date
The new Apple Watch 4 costs from £399/US$399 with GPS, and £499/$499 with cellular. The Series 3 is still available from £279/$279.
- GPS 40mm: £399/$399
- GPS 44mm: £429/$429
- Cellular 40mm: £499/$499
- Cellular 44mm: £529/$529
The new Watch goes on sale 21 September, with Nike+ and Hermes models later in the year. Click here to buy the new Apple Watch.
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