A ball return mechanism for use with a table tennis table for returning a ball to a player. Data for a snapshot is converted into a first bitmap of differential data for a remote copy. A stop arrests the cutter after the cutter has severed the tissue. The valve biasing member permits or inhibits fuel flow through the lower valve member by opening and closing an upper valve member. The user terminal has a movable image display unit for movably displaying the first image from the server; a static image display unit for statically displaying the second image; and a switch for switching the movable image display unit and the static image display unit. Hence, the coupling surface is not substantially planar.