There is provided a portable riser having an operator actuated lifting assist assembly operatively coupled to a riser deck. The constant velocity joint vent includes a flapper valve generally having a circular shape. Secondly, the crossed spiral on the surface of the cylinder provided to generate more air flow in three directions upon the rotary cylinder increases the Magnus force. The transmission member is arranged on the substrate member, wirelessly receives a test signal and provides the received test signal to the pads of the wafer through the probe terminals, and wirelessly and externally transmits an electrical characteristic signal provided from the pads of the wafer through the probe terminals. As a result, commands to change the line rate are based on a better estimate of line quality and the incidence of thrashing in the presence of recurring noise bursts is reduced, leading to increased data throughput.