How the SR16 Works

The SR16 packs advanced optical sensors, a motion sensor, and a blue LED dot-matrix display into an 8mm stainless steel ring. Here’s what it tracks, how it tracks it, and what you need to get started.

What it tracks continuously

Heart rate is monitored around the clock, with a 24-hour trend view and 7-day history. Sleep is tracked automatically — duration, sleep ratio, and a nightly sleep score with 4-day history. Steps count all day, with multi-sport modes for workouts.

What you test on demand

Blood oxygen (SpO2), heart rate variability (HRV), and stress are measured when you start a test in the app, each keeping a 7-day trend. These are quick spot-checks, not continuous background measurements — a design choice that helps the battery last 4–5 days.

The display sets it apart

Most smart rings are screenless — everything lives in the app. The SR16’s blue LED dot-matrix display shows your steps, the time, and incoming call alerts (the caller’s number scrolls across the ring). You can also trigger your phone camera with a finger gesture, use the counting mode, and find your ring via Bluetooth.

Compatibility & requirements

• Free RWFit companion app — iOS and Android
• Bluetooth connection to your phone
• Sizes 8, 9, 10, and 11 — see the sizing insert card included in the box
• Charging: 90 minutes to full in the included 200mAh charging case
• IP68 water resistance — fine for swimming and showering

The SR16 provides wellness and activity information for general fitness purposes. It is not a medical device and is not intended to diagnose, treat, cure, or prevent any disease or condition.