Abstract: A portable universal monitoring device according to various aspects of the present technology includes a portable body housing a plurality of sensor devices. The portable body is configured to be repeatedly attached to and detached from one or more objects such as a wristwatch. The portable body is configured to be discretely positioned on the object to remain unseen without negatively affecting the fit, function, operation, or comfort of the object during use. The portable body may be used interchangeably with any number of objects without requiring the objects themselves to be modified.