| 摘要 |
The screwdriver has a blade (1), the outline of which, when seen from the side, is such that behind the cutting zone which is of the standard size for a particular screw, runs so that the blade surfaces has linear contact with the edges of the screw slots (4) in the surface of the screw head (3) of screws of at least two larger sizes than the one for which the screwdriver is made.
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