| 摘要 |
<p>The closure element has a stopper unit (3) having a cylindrical or conical shaft (31). A single separate retaining ring (4) is provided on an outer jacket of the shaft. The single separate retaining ring is provided with a greater hardness than the shaft of the stopper unit. The outer diameter (d1) of the single separate retaining ring is larger than an inner diameter of the opening of the tubes (1,2). The stopper unit is made of polystyrene, while the tube is made of polypropylene.</p> |
