I love this ring. I was a little unsure initially because it was so inexpensive. I didn't expect much. My experience far surpassed expectations. Excellent battery life (~4-7 days) depending on how much you use it. 'sync' once a day, and battery stretches to 7 days. Sync multiple times a day, it drops to 4 days. Charging takes around an hour (10%'ish-100%). Pairing to qring app is seamless, and subsequent connection to (for example) google health is also simple. Tracking is reasonably accurate. Sensors should be positioned on the palm-side of my finger, and after checking against other devices, i'm reasonably confident that hr, hrv, bt and spo2 are all within 5% accuracy. I'm not sure about the sleep tracking (light/deep/rem), but even if it isn't completely accurate, the trending data is. For example, during a 48h fast, deep sleep clearly increases and rem drops, while after 'breaking the fast', rem increases.
Absolutely zero hesitation in recommending this ring and the seller!
