| 摘要 |
The specification discloses a multi-layer reinforced envelope including inner and outer sheets of thin flexible material and an intermediate sheet of reinforcing material. All of the sheets are elongated and folded along a line substantially mid-way between the ends of the sheets to define first and second portions of each sheet. The intermediate sheet is secured to only one of the inner and outer sheets and to only one of the first and second portions of that sheet.
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