Clip-on design cleans & freshens with no mess. Antimicrobial protection in the hook to resist odor-causing bacteria. Fights toilet rings & helps to prevent stains. Help maintain a clean, fresh toilet between deep cleans. Clip securely onto rim of toilet, where water flow is maximum. When used up, simply dispose the unit in the trash & replace. Cleans & freshens for up to eight weeks. Application: Automatic Toilet Bowl Cleaner; Applicable Material: Ceramics; Enamel; Metal; Chemical Compound: Sodium C14-16 Olefin Sulfonate; Sodium Dodecylbenzenesulfonate; Dirt Types: Soils; Odors.