| 摘要 |
The present invention pertains to a screw comprising an enlarged head and a shank with threads. In particular, the enlarged head has a bottom surface comprising a plurality of ribs extended from the outer periphery thereof to the shank, thereby providing with a good resistance of extraction and a good waterproof effect. Additionally, due to the ratio of the outer diameter of the shank to the outer diameter of the head being 1:3.5~5.5, the debris extruded out of the object hence can be covered and squeezed beneath the enlarged head, so as to maintain a clean appearance.
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