By comparing these 2 products I must say that the Wellue O2 ring and Withings pulse oximeter are the best pulse oximeters in the market today.
Despite some shortcomings as a pulse oximeter , it's good to mention that, overall, the new Withings Pulse O2 bracelet with updated firmware is a solid, high-quality fitness tracker with pulse oximeter function on your wrist! But if you want to get accurate saturation measurement in a day and night time then you must choose a Wellue O2 ring.