Expanded metal pleat support grid ( AmAir 300X) • High loft media increases dust holding capacity • Excellent primary filter to prevent dust build-up on AmAir AmAir ® ® 300X ® ® HT ® heating and cooling coils, fans, and ductwork • Excellent prefilter for higher efficiency filters • Directly interchangeable with disposable panel filters, media pads in metal frames, or permanent filters used in built-up filter banks and side access systems. No modifications are necessary to frames or latches • 4" filters have pleat stabilizers to ensure uniform spacing and increase rigidity ( AmAir ® 300X)