These are robust filters made of some layers of synthetic mesh that are non woven, sandwiched in between. The pleats are V shaped and rounded well to increase the dust arrestance of filters. Media is further enforced by metal expanded mesh to give extra rigidity to pleats so that peats would retain their shape at higher pressure drop.

Spectra Cell Compact filters offer substantial advantages over conventional filters, not the least of which are higher flow capacities, less space, reduced resistance to flow, and greatly enhanced dust holding capacities. 
It serves as an excellent final filter for AHU, air intake systems of combustion engines and as a final filter for HVAC systems.
An innovation for a better interior environment is the Mini Pleat Filter which guards against all types of particles, aerosols, bacteria, and coarse grit.

The Spectra Cell Deep pleat is a ruggedly constructed, heavy duty filter which has a higher media area and  ensures extremely high dust holding capacity with lower operating pressure, stable performance at variable airflow. Filter media layers with aluminium separators makes the air to flow through the entire media area and increase the lifetime of the filter.

High efficiency deep pleated HEPA filters are used for removal of airborne contaminants, including fine dust, smoke, soot and microorganisms.