Oura launches Ring 5, world’s smallest smart ring, as it heads towards IPO

Finnish-US startup has sold 5.5m rings worldwide since it was founded in 2013 and is valued at $11bn

Stylish Finnish-American smart ring company Oura may be the darling of wearables, adorning the fingers of celebrities and sportspeople, but it is not resting on its laurels as it heads towards an IPO later this year. This week it launched the world's smallest smart ring, the Ring 5, its latest evolution of the device that defined a whole category.

The Ring 5 is 40% smaller and with longer battery life than the highly popular Ring 4. It also promises to squeeze the health-tracking features of a smartwatch into a less techy piece of jewellery just 2.28mm thick, focused on sleep, stress, readiness and heart health.