Ultrahuman Ring Air Swatch Sizing Kit

Select the optimal finger and the hand intended to wear the ring on. Try on an index, middle and ring finger to feel the best fit. It's not recommended to wear the ring on a thumb or little finger as it is less accurate there. Opt for a secure fit by positioning the sensor ridges on the palm side of the finger and make sure it does not rotate easily. Ensure the ring sits comfortably yet securely at the finger's base, providing stable contact without causing discomfort. Ideally skin should touch the full inner circumference of the ring. If skin under the ring touches and moves along with it when twisting the ring, it's a good fit. Once you’ve picked a size that fits, try a size up and down to be sure. 

Keep the ring on overnight as fingers tend to naturally expand and contract going about a day. A minimum of 2 nights is recommended to ensure the ring size fits best. It is natural for finger size to fluctuate every day for a variety of reasons such as blood flow, fluid retention, temperature changes, sickness and even the phase of your menstrual cycle can affect ring size. Pay attention to how it feels during various tasks and at different times of the day. As the ring fit changes throughout these two days, you might notice discomfort if finger size fluctuates significantly throughout the day. Instead of picking a looser ring, it is recommended to find a ring that fits snugly on at least two different fingers, so you can switch when one fluctuates. Getting a snug fit is crucial for accurate data tracking, ensuring maximum comfort and accuracy in tracking biomarkers in the long term. 

If you’re confused between two sizes, it could be from not trying each size on all fingers. Try on all sizes that fit on index, middle and ring fingers on both hands to arrive at the size that works best. For the best ring fit, choose fingers where the base and knuckle have similar widths. Avoid fingers with narrower bases than knuckles as this can lead to misleading fits. A ring may feel snug when passing the knuckle but sit loosely at the base where it actually rests. 

If you must use a finger with a narrower base, carefully rotate the ring while passing the knuckle. If encountering significant resistance, consider trying a different finger or selecting another ring size. Perform a simple elimination test: If the larger ring feels loose at any point during the day, opt for the smaller size. A loose ring can’t accurately capture biomarkers. If at this point you are still undecided, then choose a ring that seems like a good fit on more than one finger.