A smart ring is a compact, screenless wearable that packs advanced biometric sensors into a form factor no larger than a standard piece of jewelry. Unlike smartwatches, these devices prioritize passive, high-fidelity data collection—specifically targeting heart rate, blood oxygen levels, and skin temperature from the thin skin of the finger, where pulse signals are often clearer than at the wrist. By offloading the visual distractions of a screen, smart rings typically achieve superior battery life (often 4–7 days) and focus their utility on long-term health trends, such as sleep stage analysis, recovery tracking, and menstrual cycle prediction, through a tethered smartphone app.