G1 G4 Pleated Panel Air Pre Filter for Industrial Air Filtration and Customizable Filtration with ISO Approval Air Pre Filter G1 G4 Pleated Panel Filter ISO Approved for Industrial Air Filtration Systems Air pre-filters are essential HVAC pre-filters designed to improve the air quality in your plant. This panel filter has a double-sided mesh structure that can capture dust and other contaminants very efficiently before they enter your air conditioning system. This pre-filter