| 摘要 |
The present invention generally relates to a screw, and more particularly to the improvement of a drive recess of a screw head or a bolt head. The drive recess of the screw head includes four symmetrical arc-shaped grooves and a square groove formed at the center of the arc-shaped grooves. Thus, the types of slot, cross, cross-square combination, square and double-cross of the drive bit of the conventional screw driver bit can be adapted to insert into and engage with the drive recess of the present invention. Particularly, when the screw driver bit having arc-shaped drive bit is simultaneously used, it is easy to control the screw during locking and to generate larger driving torque, thereby achieving the object of practical utility and economizing effort.
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