The Ultrahuman Ring Air in Aster Black, Size 13 is a lightweight titanium smart ring that tracks sleep, recovery, skin temperature, and movement, with personalized nudges in real time. Up to 6 days of battery. Sleep Index, recovery, women's health, and a stimulant window recommender No subscription — lifetime access to your data in the Ultrahuman app. Water-resistant to 330 ft This description was generated by AI and reviewed for accuracy.