The top part of one inner bolt which matches the blank hole channel of the outer hollow screw is also conical. The rear is provided with a thread and a tetragonal body for holding.
一与外空心螺钉的盲孔道相匹配的内螺栓，内螺栓的尖端部位亦为锥形，尾部设有螺纹和供握持用的四方体。
The top part of one inner bolt which matches the blank hole channel of the outer hollow screw is also conical. The rear is provided with a thread and a tetragonal body for holding.
一与外空心螺钉的盲孔道相匹配的内螺栓，内螺栓的尖端部位亦为锥形，尾部设有螺纹和供握持用的四方体。
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