| 摘要 |
<p>A strip adapted to form a tube by helically winding and having a series of longitudinal ribs upstanding from a base on the strip and transversely spaced thereon in which one rib has a bulbous end portion and another has a bulbous longitudinal socket to form interengaging means when helically wound, all or some ribs optimally defining a hollow whereby limited lateral stretch at the join and ribs is permitted. The hollow can be closed by a flap.</p> |
