"Wormtail," said Voldemort, with no change in his quiet, thoughtful tone, and without removing his eyes from the revolving body above, "have I not spoken to you about keeping our prisoner quiet?"

In the industrial field, a number of product parts structure had used normal uniform thickness revolving curved surface body.

It has the same revolving 90 degrees movements, what is different is the cock body is the spheroid, has the circular through hole or the channel passes its spool thread.