Filter Media Bag 18" x 24" (45cm x 60cm) 4mm 5/32", Pond and Aquarium Filtration Pond H2o's Water Garden Pond & Aquarium Filter Media Bag with a drawstring and plastic toggle to hold closed. Strong High quality materials designed to hold all types of filter media. Filter Media Bags allows custom chemical filtration. Simply fill the media bag with the filter media of your choice and place in your filter for enhanced aquarium or pond water quality. Inexpensive and versatile filter media bag is made of 100% polyester featuring a top drawstring for easy closure. Black micro fine mesh bag is great for biological rings, volcanic rocks, coral sands, ceramic rings, activated carbon, ammonia remover resins, or any of your favorite aquarium or pond filter media. Use media-filled bags in power filters, canister filters, or wet/dry filters to customize pond filtration. Re-usable, simply rinse with water and refill as needed. PondH2o Quality! 18" x 24" (45cm x 60cm) 4mm 5/32" High Quality Black Mesh Drawstring closure Easy to clean or change Holds any type of Filter Media Open mesh to allow water to free flow