The ELECTRA GOLD provides over 94% Dust Arrestance in a premium quality Extruded Stainless Steel, Gold Anodized frame with a durable and attractive finish. At the heart of this filter are three layers of high arrestance material sandwiched between 2 layers of expanded steel. A special Impregnated black Polypropylene has an EPA registered anti-microbial material to inhibit mold and bacteria growth while the center non-woven layer retains debris in a maze of fibers designed to maximize air flow even when soiled. Rated by independent testing laboratory at over 94% peak arrestance, this filter has 10 times the arrestance of a disposable fiberglass filter.