Xiaomi Smart Band 8. This activity tracker features an AMOLED display with a diagonal of 4.11 cm (1.62 inches). It is a clip-on/wristband device with an oval form factor and comes in black graphite. The battery life is up to 16 days with typical mode usage. It offers adaptive display brightness, a high refresh rate, quick charge, and comprehensive all-day health monitoring, including fresh and fun watch faces.