| 摘要 |
<p>An anti-rotation device (7; 107) for use in a well tool, for example a top plug (1) or a bottom plug (101), has a tapered male member (7; 107) having a corrugated outer surface (8; 108) which can enter a corresponding recess (114; 214) in another well tool to inhibit relative rotation therebetween.</p> |
