No More Scrubbing Chemical free Toilet Bowl Descaler Lasts 5 Years. Don"t waste money on harsh chemical cleaners or spend your time scrubbing. With every flush (up to 50,000), this remarkable cartridge helps loosen and prevent lime scale build-up, thus reducing fungus, mildev4 bacteria and stains. Hidden in the flow-through cartridge are advanced hydro.mineral magnets and Bact-0-Bane antibacterial fibre. They work without adding anything to the water, or  removing anything from it. Measures 4 x l~I494 x 1/2W. Use two in very hard water. The world's easiest toilet bowl descaler, just drop it in the tank and it  goes to work - preventing mineral build-up and stains.