| 摘要 |
A first tubular member (11) of an extension device (1) includes a first tubular body portion (16) provided with protruding portions (17) which are so formed on the inner surface of the first tubular body portion (16) as to protrude therefrom and extend from one axial end to the other end of the first tubular body portion (16). A second tubular member (12) which is capable of moving back and forth along the inner surface of the first tubular member (11) includes a second tubular body portion (27). A rotation prevention portion (28) adapted to come into contact with the protruding portions (17) and thereby prevent rotation of the second tubular member (12) is formed on the outer surface of the second tubular body portion (27) so as to rise therefrom. The extent to which the protruding portions (17) protrudes is nearly the same as the thickness (i.e. the height) of the rotation prevention portion (28). <IMAGE> |
