To order ASHRAE-compliant FiltersRx, simply log on to company's website. Aluminum type, made by layering corrugated mesh, comes in 0.5, 1, and 2 in. thicknesses. Pleated version consists of 100% synthetic material bonded to metal grid, eliminating flutter and maintaining pleat shape. Pocket type, with moisture-resistant media, comes in 60-65%, 80-85%, and 90-95% efficiencies. Metal-framed box filter tolerates turbulent flow, moisture, and heat. HEPA version, with particle board or metal frame, maintains 99.97% or 99.99% efficiency.