| 摘要 |
<p>The envelope may be of any conventional sort and has a wire made from steel, or nylon or string fitted to the underside of the flap. This may be fitted permanently by glueing. One end of the wire adheres to the corner of the envelope, which is marked on the outside as the corner to open. Tearing the corner results in the end of the wire being held in the hand after tearing, and pulling sideways on the wire then tears the flar off without the aid of a letter opening knife.</p> |
