| 摘要 |
PROBLEM TO BE SOLVED: To provide a screwdriver usable for a screw of a (+) groove, a screw of a (-) groove and even for a dual service screw. SOLUTION: A projecting part 1a is projected in a central part of a tip 1, the tip is formed into a projecting shape, and when used for a screw of a (-) groove, the tip 1 is fitted to the (-) groove, and when used for a screw of a (+) groove, the projecting part 1a is fitted to an orthogonal one groove of the (+) groove. When used for a dual service screw 7, the projecting part 1a is fitted to a recessed part 8c of the groove center, and the tip 1 is fitted to a long groove 8a.
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