| 摘要 |
<p>The invention relates to a face mask comprising a face piece shaped to cover the mouth and nose of a wearer, an exchangeable filter covering the interior of the face piece and consisting of first and second layers of filter material lying one against the other respectively to intercept particles of greater and lesser size, and at least one fastening device carried by the face piece and arranged to pinch the first layer of filter material against the interior of the face piece and to be covered by the second layer of filter material.</p> |
