A flexible device includes two devices and a flexible interface. The two devices each include electrical components assembled therein. The flexible interface is coupled to the two devices such that the flexible interface connects the two devices to each other. When the two devices are positionable on a human body, the flexible interface provides stretchability and extendability so that the two devices can be set on two opposite sides of a protrusion site of bones of the human body, allowing for stretching and contracting of the human body to provide an effect of suiting the ergonomic needs.
