BPM Core is a digital monitor intended for use in measuring blood pressure, heart rate, and ECG in an adult population with an arm circumference ranging from 9 inches to 17 inches (22 cm - 42 cm).
https://support.withings.com/hc/zh-cn/sections/6215770022289-BPM-Core
https://support.withings.com/hc/zh-cn/sections/360002731973-FAQ