Apple Watch Series 8 features advanced health sensors and apps, so you can take an ECG, measure heart rate and blood oxygen,2 and track temperature changes3 for advanced insights into your menstrual cycle. And with Crash Detection, sleep stages tracking, and advanced workout metrics, it helps you stay active, healthy, safe, and connected. • MNUQ3LL/A • Screen Size: 45 millimeters • Touch Screen: true • Operating System: Apple iOS • App Compatible: true • Global Positioning: GPS • Metrics Measured: Blood oxygen, Electrocardiography (ECG), Skin temperature. • Water Resistant: true • Maximum Depth of Water Resistance: 164 feet • Series: 8 GPS 45mm Starlight Aluminum Case with Starlight Sport Band - M/L • Condition: **refurbished**