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.Geek Squad Certified Refurbished products are thoroughly, painstakingly and lovingly tested, so you can be sure that your device will work right, right away. | Geek Squad Certified Refurbished Apple Watch Series 8 (Gps + Cellular) 45Mm Aluminum Case With Midnight Sport Band | | M/L | | 2022) | Midnight | Best Buy