Oura on Thursday announced its latest smart ring, one that it says is the smallest offered by any company.

The Oura Ring 5 will be 40% smaller than Oura’s previous generation ring, the company said. The ring will still have the same level of sensing, tracking and accuracy as the previous generation, it said.

“We have finally achieved what I think seems like a real technological miracle,” Oura CEO Tom Hale said in an interview with CNBC’s Andrew Ross Sorkin on Thursday. “This is what our members have been asking us for, for years.” he said. “This was a hard technological challenge. There are laws of physics involved with the sizes of batteries and the ability to pack all the electronics, the sensors; the geometry is different because it’s so small,” he added.

The ring, which will start to ship on June 4, will be priced at $399 for base finishes and $499 for premium finishes like gold and brushed silver. The company will also be launching a portable charging case for the new ring, priced at $99.

“I’ve been wearing it for six months with a cover and going to the gym with it and working out, and not even feeling it on my body, and that is first step I think in building something which is truly a transformative wearable,” Hale said.

Oura has been named to the CNBC Disruptor 50 list four times, including No. 14 in 2026. Last week, Oura confidentially filed a draft of its IPO prospectus with the Securities and Exchange Commission. It did not provide a timeline for an IPO.