The Apple Watch Series 4 is the first over-the-counter consumer product that can be used for an electrocardiogram reading. At present this heart-monitoring feature is approved for the US market only, but it will notify you if your heart rate is too high or too low.

But the Series 4 is more than that. Design tweaks make it ergonomic, and despite a bigger display it’s still thinner than the Series 3. Continue reading here: