(Bloomberg) -- Celebrities like Will Smith and Shaquille O’Neal are among the investors who have pledged a total of 20 million euros ($23 million) to Oura Health, a Finnish startup that’s tapping into the surging wellness market with a health-tracking ring.

The latest funding round, led by Michael Dell’s MSD Capital, brought in 4.5 million euros, which will be used to ramp up production.

With prices starting at 314 euros and going all the way up to 1,049 euros for the diamond version, the Oura ring’s sensors measure blood flow, temperature and body movement and display the data in a smartphone app. The advantage of the ring over other tracking wearables like bracelets and smartwatches is that it can easily be worn while sleeping.

“Oura has identified a challenge that faces us all,” Dell said in an emailed statement on Monday. That’s how to get “enough high-quality sleep.”

Apple Inc. is among the industry giants that have been seeking to capitalize on the market for wearable health-tracking devices, which despite some privacy concerns is expected to grow to $11.2 billion by 2025, according to a February report from BIS Research, a market intelligence firm.

To contact the reporter on this story: Kati Pohjanpalo in Helsinki at kpohjanpalo@bloomberg.net

To contact the editors responsible for this story: Tasneem Hanfi Brögger at tbrogger@bloomberg.net, Nick Rigillo

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