The present invention is directed to a passive ascent rate monitor that is operable to determine a diver’s rate of ascent and generate a signal indicative of the determined ascent rate. The antennas differ from one another in terms of horizontal orientation and cover all horizontal directions. The signal plug is projected from the case for plugging in a corresponding upstream port, which is normally a USB B type socket, on a predetermined hub. The bearing has a plurality of channels defined in an outer surface thereof, for guiding the escaping oil to return to an oil reservoir defined in a bottom of the central tube. An insert has a second hardness and is seated in the recess. Further, a video may be selectively played to display portions of most interest to given demographic categories, as indicated by voting patterns of those categories.