The Series 1100 pleated filters incorporate a 100% synthetic media with an ASHRAE 52.2 MERV 11 (minimum efficiency reporting value). The 1″ and 2″ filters handle velocities up to 500 FPM -the 4″ filters up to 625 FPM. The media is chemically bonded to a metal grid on the air-exiting side., preventing fluttering, and maintaining uniformity of the pleats. The filter pack is enclosed in a heavy-duty, moisture resistant, die-cut frame that will not warp, crack or distort under normal operating conditions. Diagonal front and back media retainers are an integral part of the filter frame. the media pack is bonded to every part of the frame, preventing any possibility of air by-pass. Integral pleat separators on the 4″ filters provide additional pleat stabilization for the most demanding applications. The Series 1100 filters accumulate heavier, more restrictive particles at the bottom of the pleats, leaving the sides open longer for effective filtration. The Series 1100 filter is engineered to provide maximum efficiency. In general, deeper pleats result in longer filter life and more time between changeouts. These filters can be used without modification in side-access filter housing or built-up filter bank. They offer better efficiency than conventional permanent or disposable flat filters. The Series 1100 filters, when used as pre-filters, substantially extend the life of more expensive high efficiency filters. They are the perfect filters for residential, commercial and industrial use.