A gas spring comprising a cylinder body filled with compressed gas and an upright rod passing through a rod side end wall member of the cylinder body. The base plate defines two first slots. The baseband processor receives a broadcast signal including mobile service data and main service data, wherein the mobile service data configure a Reed-Solomon frame. Thus, the slidable member facilitates absorption of the upward force acting on the downhole tool. The partially-depletion-type transistor has a threshold voltage, which is substantially equal to that of the transistors in the logic circuit section when no potential is applied to the body contact portion and which is higher than that of the transistors in the logic circuit section when a potential is applied to the body contact portion. The operating finger of the operator’s hand is displayed as a finger image on the display unit under control of the capture controller and the image controller in a manner that a finger tip of the operating finger occupies only a small portion relative to the size of the operation panel.