| 摘要 |
The invention provides an air filter with an integral rigid edge. The filter uses a pre-cut sheet of non-woven synthetic filter material. The sheet has a generally rectangular central portion and four outwardly extending side portions. Each side portion is compressed to make it thinner, denser and more rigid than the central portion. The side portions are rolled or folded upon themselves toward the central portion to form a rigid edge around at least a part of the central portion. A method for making the air filter is also provided.
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