An endoscope flexible tube comprises: a tubular structure having flexibility; and a shell layer on an outer peripheral surface of the tubular structure, wherein the shell layer has a two-layer structure including a rigid resin layer of a rigid resin and a soft resin layer of a soft resin, and wherein the two-layer structure is maintained over the entire flexible tube in its length direction. A follower is slidably disposed in the housing, and includes an inclined surface for engaging with an inclined surface of the seat, and for moving the follower up and down relative to the housing when the follower and the housing are rotated relative to the seat. It is also common to have a larger manifold or supply line branch off into smaller branch lines through the use of \u201cT\u201d fittings. Depending on the existence of these unusual data patterns, the optical disk is judged as a legitimate production or an illegal production.