Pleated Panel Filters Pleated filters were originally designed to be able to provide increased surface area to a panel type filter in order to provide longer service life. The pleated filter has become one of the most frequently used filters in the HVAC industry. The pleated filter is available in two efficiencies, 25-30% and 40-45% and in three capacities, economy, standard and high. The pleated filter is available in 1", 2", and 4" depths. At 500 fpm, the initial resistance is 0.26" w.g.