A flexible membrane is situated within a rigid or semi-rigid cap. The signal path may be a portion of an hybrid fiber optic and cable network so that other signal paths in the HFC network may service subscribers in other areas. Thus, the mass flow rate may be determined based on the corrected pressure reading and a measured volumetric flow rate. The visual cues move along the row of letters in variable offsets based on a rate of input of the user actions. As a result, the battery is charged.