A composite filter media includes a fibrous filtration layer of randomly oriented fibers and one or more pleatable stiffening layers which enable the composite filter media to be pleated and hold or retain its pleats. The pleatable stiffening layer(s) may enhance the dirt holding capacity of the composite...http://www.google.es/patents/US5993501?utm_source=gb-gplus-sharePatente US5993501 - Composite filter media
