Oura launched the Gen 5 Oura Ring on Tuesday as the company’s smallest smart ring yet, cutting the device’s volume by 40% from Oura Ring 4. The new model is meant to be slimmer, lighter and more comfortable while still tracking health around the clock.

That redesign is the reason people are searching for it now. Oura says the ring was rebuilt from the inside out to deliver more accurate, continuous insights in a compact, jewelry-like shape, and Tom Hale said the goal was to make a ring people could wear without thinking about it. The company also said it found about 6 mm to be the preferred width for style and comfort, and for a wide range of activities, which helped define the new design.

The engineering behind the smaller body is doing a lot of work. Oura says the Gen 5 Oura Ring uses precision-engineered, low-profile sensor domes, more efficient LEDs and 12 stronger, more accurate signal pathways. The LEDs are also rotated 180 degrees to shorten the optical path for red, infrared and green light, while the company says the ring’s more durable finish is part of the overall refresh.

Still, the cleaner silhouette hides a complication. Oura says the ring is much smaller, yet the sensors that hold the LEDs and photodiodes are slightly larger inside than those in Oura Ring 4. J-T Mäkinen said the engineering team had to push the LEDs and photodiodes closer to the skin’s surface and through the metallic layer because the ring is so thin, a tradeoff that shows how far the company had to go to keep the device small without giving up signal quality.

That is the story of this launch: Oura is betting that a smaller ring can still improve health sensing, not just fit more neatly on a finger. The company says the new model balances signal strength, lower power use and better contact with the skin, and describes it as its most accurate generation yet. What Oura has not yet said is when the ring will go on sale or what it will cost, leaving the biggest practical details of the release still open.