DREHEINHEIT, EINSETZVORRICHTUNG, EINSETZKÖRPER, EINSETZVORRICHTUNG MIT DARIN POSITIONIERTEM EINSETZKÖRPER UND EINSETZSYSTEM MIT EINEM EINSETZKÖRPER UND EINSETZVORRICHTUNG
A cylindrical rotation unit attachable to an elongated insertion unit which includes a base in which a central axis is defined, and a rotation member provided on an outer circumference of the base movably in an axial direction of the central axis relative to the base and rotatably around the central axis in response to the rotation of a rotation force transmission portion which is rotatable around a longitudinal axis parallel with the central axis of the base includes: an engagement portion attachable to and detachable from an outer circumferential surface of the base； and a contact portion which is provided to contact on the rotation member away from the engagement portion and which disposes the rotation member on an outer circumference of the rotation force transmission portion while the engagement portion is engaged with the outer circumferential surface of the base.
