| 摘要 |
<p>The button has at least three fastening or stitching holes which are all in alignment, pref. set in an axis of symmetry of the button at even spacing from each button. The two outer holes can be set near the edge of the button to prevent the button from twisting round during use. The cross-sectional area of the middle stitching hole is pref. twice as large as that of the two outer holes to allow for the double thickness of fastening thread when stitching through three holes.</p> |
