A pulse oximeter ring is a compact, wearable health device designed to continuously monitor blood oxygen saturation levels (SpO_{2}) and heart rate with medical-grade precision from the base of the finger. Unlike traditional bulky fingertip monitors, the ring form factor utilizes a flexible, lightweight design—often made of medical-grade silicone—to ensure comfort during overnight sleep tracking or long-term daily use. The device operates using transmissive or reflective photoplethysmography (PPG), emitting specific wavelengths of red and infrared light through the skin to measure the light absorption of oxygenated versus deoxygenated hemoglobin. Most modern units feature a built-in vibration alarm that discreetly alerts the wearer if oxygen levels drop below a pre-set threshold, making it an essential tool for individuals managing sleep apnea or respiratory conditions. Data is typically synced via Bluetooth to a smartphone application, where users can view detailed trends, sleep stages, and cardiovascular health metrics through intuitive dashboards. These rings are powered by rechargeable lithium-ion batteries that often last several days on a single charge and are engineered with high-motion tolerance to maintain accuracy even when the user is moving. The sleek, unobtrusive profile allows for 24/7 monitoring without interfering with manual tasks or causing the discomfort associated with clip-on sensors. By providing real-time physiological feedback, a pulse oximeter ring empowers users to take a proactive approach to their respiratory well-being and overall systemic health.