| 摘要 |
Either the base part 4 or the coupling part 3 includes a first coupling member 3a which is substantially circular in cross-section in a radial direction perpendicular to the central axis and has a diameter of a first length D1, while the other of the base part 4 and the coupling part 3 includes a first holding member 4c which, with its inner circumferential surface having a substantially circular shape in cross-section in the radial direction, holds the first coupling member 3a so as to surround its outer circumferential surface. The inner circumferential surface of the first holding member 4c is partially opened in the radial direction, and an opening width of an opening part 4g of the first holding member 4c, which is elastically deformable, is narrower than the first length D1. |
