Fold-flat personal respiratory protection devices are provided. The devices have a flat central portion having first and second edges, a flat first member joined to the first edge of the central portion through either a fold-line, seam, weld or bond, said fold, bond, weld or seam of the first member...http://www.google.es/patents/US6536434?utm_source=gb-gplus-sharePatente US6536434 - Flat-folded personal respiratory protection devices and processes for preparing same
Flat-folded personal respiratory protection devices and processes for ...
