Frieling Gold Coffee Filter is high quality 19/10 stainless steel, foil-coated with gold tone. The foil is designed with minuscule opening to allow the flavor carriers (colloids) to pass while holding back all solids. Easy to clean, no residue build-up and no waster. Think of foil filters as "smart" filters", they know you want desirable flavors and aromas in your cup, but not the undesirable sediment. Gold Filter #4 fits all coffee machines that use a #4 cone filter for 6 - 12 cups.