| 摘要 |
<p>A cork of hard PVC, ribbed to hald its height from its free end and conicaly tapering in the ribbed region from the free end, has an inner construction. The inside dia, is smallest at the transition between the ribbed and unribbed parts, and the floor has an annular sealing rib. Pref. the plastic is treated with a magnetisable metal. It is more flexible and has wider uses than corresponding metal corks.</p> |
