Apple Watch Series 8 features advanced health sensors and apps, so you can take an ECG¹, measure heart rate¹ and blood oxygen², and track temperature changes³ for advanced insights into your menstrual cycle⁴. And with Crash Detection, sleep stages tracking, and advanced workout metrics, it helps you stay active, healthy, safe, and connected. See Dimension section below for band sizing information. | Apple Geek Squad Certified Refurbished Watch Series 8 (Gps) 45Mm Aluminum Case With (Product)Red Sport Band | | S/M | PRODUCT | 2022) | RED | Best Buy