| 摘要 |
<p>Watch case has a frame with a plastic periphery and a radial annular shoulder, a base, a metal ring covering the frame and its outer face, a recess in the ring receiving the shoulder so that the ring and frame are inseparable, and an annular recess between the ring and the frame receiving a seal. The plastic is pref. a copolymer of acrylonitrile, butediene, and styrene, or acrylonitrile, styrene, and acrylic ester, or styrene and acrylonitrile. It may alternatively be of polyamide and glass fibres.</p> |
