Apple was forced to remove the blood oxygen monitoring two years ago amid a patent dispute, but a software update coming later today will revive the feature.

Thanks to new OS updates rolling out now, you can once again use your Apple Watch to measure the oxygen level in your blood.

The change doesn’t affect previously sold models with the original version of the feature or units bought outside the U.S.

A new sensor could soon allow hospital patients' blood oxygen levels to be checked via their breath. The technology is claimed to be more reliable and less painful than existing traditional methods.