| 摘要 |
The invention relates to a flat transparent envelope comprising a rectangular, transparent cover sheet (1) and a rectangular, preferably transparent backsheet (2). The cover sheet (1) and backsheet (2) are flexible films joined together along at least two but no more than three of their edges so that the envelope is open along at least one of the sheet edges. The edges of the joined sheets are situated in the envelope plane and the transparent cover sheet (1) consists entirely of a magnifying material.
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