Marineland PA11484 Canister Filter Ceramic Rings, 140-Count Provide Porous Surface Area for Support of Biological Filtration Do not clean with soaps or abrasives and never rinse with unconditioned tap water 140 rings Provide Porous Surface Area for Support of Biological Filtration Do not clean with soaps or abrasives and never rinse with unconditioned tap water Bio-rings do not require replacement