Designed to penetrate, dissolve and remove odor-causing residue that can occur in all washing machines Specially formulated tablet dissolves slowly, lasting throughout the entire wash cycle and breaking up residue better than bleach Safe to use with Front Load Washing Machines and Top Load Washing Machines - High Efficiency (HE) and Conventional Washers Use once a month to keep your machine fresher and clean, Product has a shelf life of 2 years from the production date that is printed on the item. Septic tank safe. Note: The date on the item is production date not expiry date.