| 摘要 |
A screw for fastening boarding arrangements or the like at a distance in front of an underlying surface contains two threads which are of the same external diameter and the same pitch and are separated from each other by a thread-free portion. One thread portion extends from the tip of the screw, and the second thread portion reaches directly up to the screw head. The length of the thread portion directed towards the screw head is independent of the length of the screw. |
