Apple Watch S4 has a host of new health features that could genuinely help to save lives. Not only is it the first consumer device with the ability to perform an electrocardiogram test (ECG) and send the results to your doctor, it can also help you out in case of a dangerous accident – but only if you’re old enough to trigger the feature, or knowledgeable enough to switch it on yourself.

Fall Detection takes advantage of the lightning-fast processor in the latest-generation Apple Watch – along with improved gyroscope and accelerometer capabilities – to monitor your movements to the point where it can tell if you have a nasty fall.

If the device detects a fall it will throw up a warning screen asking if you’re okay, along with a button to instantly call emergency services. If your fall was bad enough that you don’t get back up again, Apple Watch will automatically phone emergency services on your behalf after a minute of inactivity. It will message your location to your registered emergency contacts, too.

Apple says its algorithm been trained to recognize the difference between fake falls and accidental slips and trips, but the feature can still produce false positives if you’re taking part in sports. Better safe than sorry, eh?

This is a great feature with the potential to help a lot of people – but it’s only activated by default if you’re at least 65 years old. Younger users can toggle Fall Detection on manually from the Watch app on their iPhone, from the My WatchEmergency SOS section.

If you’ve picked up the latest Apple Watch already, consider this a recommendation to switch Fall Detection on. You never know when you might need it.