A ring-type wearable device is disclosed. The disclosed ring-type wearable device comprises: an outer ring member; an inner ring member separably inserted into the outer ring member; a sensor unit disposed in the outer ring member; and a control unit disposed in the outer ring member so as to be electrically connected to the sensor unit, wherein the sensor unit can maintain constant sensitivity in correspondence to the thickness of the inner ring member.

A ring-type wearable device is disclosed. The disclosed ring-type wearable device comprises: an outer ring member; an inner ring member separably inserted into the outer ring member; a sensor unit disposed in the outer ring member; and a control unit disposed in the outer ring member so as to be electrically connected to the sensor unit, wherein the sensor unit can maintain constant sensitivity in correspondence to the thickness of the inner ring member.

Methods, systems, and devices for a functional cover are described. A removable cover (e.g., a functional cover) for a wearable ring device (e.g., a ring wearable) may include one or more electrical components positioned at least partially within the removable cover. The removable cover may further include a first electrical component exposed to an external surface of the removable cover, the first electrical component configured to contact (e.g., physical and electrically contact) a second electrical component of the wearable ring device, such as when the removable cover is in a mounted state on the wearable ring device. The first electrical component may be further configured to transfer electrical current, data, or both, between the one or more electrical components of the removable cover and one or more additional electrical components of the wearable ring device.