A subscriber unit, including an antenna array and an antenna array interface coupled to the antenna array, is described. The sensor apparatus includes a sensor that senses one of the fluid properties. In one implementation the control application stores the one or more advertising links and the first information in a database and determines the geographic location of the computing device. In response to a request for guidance, actions performed by the current user prior to requesting guidance may be used to retrieve, from the repository, one or more sessions containing related actions. The rotational joint is constructed to pair the first oblique surface and the second oblique surface so as to provide angular sliding in between and thus to alter angling between the socket assemble and the common plug.