| 摘要 |
The screw (1) is of the type provided with helical screw threads. The threads in the forward end (2) of the screw are in opposite direction to those in the rearward end (3). The outside diameter (d1) of the rearward end (3) is preferably greater than that (d2) of the forward end (2). Screw is partic for fixing e.g. decorative wall panels. |
