Attributes: Contains an aluminum foil pad between two pieces of expanded aluminum. Usage: This washable aluminum filter is used in ducted and ductless range hoods and microwave ovens to remove grease from the air. Maintenance: We recommend that the filter be washed as often as required to prevent grease build up and a resultant decrease in air flow. Soak in a solution of hot water and degreaser for 10-20 minutes. Agitate gently to remove loosened grease. A residue of grease on the filter after washing is acceptable as this helps retain grease.