| 摘要 |
<p>The device has an external thread attached at a lower end of an omega-shaped ring (1) from introduction of a groove up to the end of the groove. An opening is formed in another omega-shaped ring (6), and connected with another groove of the latter ring. An internal thread is formed in an end surface that limits the latter groove. A screw extends through the latter groove, and is screwed into the internal thread. Another internal thread is provided in an inner side of the latter ring, and is screwed in the external thread.</p> |
