Media bags allow convenient custom chemical filtration. Simply fill Skimz Xtend-Life nylon media bag with chemical media of your choice and place in your filter for enhanced aquarium water quality. Inexpensive and versatile media bag is made of 100% nylon featuring a top drawstring for easy closure. 300-micron fine mesh bag is great for activated carbon, ammonia remover resins, or any of your favorite aquarium filter media.