Tech specs 
MaterialThe second generation Oura rings are wrought out of titanium. They have a seamless, non-allergenic inner molding. The rings come in Silver, Black, and Stealth. Black and Stealth rings have a DLC coating while Silver rings have a PVD coating and a Chromium Nitride coating.
Battery lifeup to 48 hours (Lithium-Polymer cell)
RechargeableYes via charger. Full charge takes a maximum of 60 minutes.
Water resistancewaterproof to 50 meters
Sensors3D accelerometer, optical heart rate sensor (measures pulse waveform)
Activity trackingWhen you go to sleep, the ŌURA ring analyzes the quality of your rest and recovery by measuring your heart rate (optically), respiration rate, body temperature, and movement. In addition to detecting the smallest hand and finger movements, ŌURA continuously monitors your heart rate, pulse amplitude and small variations in heartbeat intervals throughout the night. With this information the ring can detect changes in your breathing rhythm and other variables that reveal what is really happening in your brain while you sleep.
While you are awake, ŌURA monitors the duration and intensity of your activities, and the time you spend inactive.
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