https://getwellue.com/pages/o2ring-oxygen-monitor

Price: $165.00

Description:

Wear the ring, it will automatically start to track your overnight blood oxygen saturation, heart rate and body movements continuously. 

Don’t worry about skipping any hypoxic events or abnormal heart rates. The built-in alarm will vibrate and remind you of low oxygen levels or irregular heart rates happen. Noise-free, only wake you when needed. Protect your partner’s sweet dream.

The app shows a report of how long your oxygen is below 90%; how many times during a night your oxygen drops over 4%.