Crystal Clear Aquatics AAD00285 Polypropylene Media Bag with Draw String, 150-Micron, 16-Inch by 7-Inch This 150 micron mesh bag with built-in drawstring is used to hold media in aquariums and ponds Made of polypropylene material It is industrial grade, machine washable and re-usable Can be used with any media including all types of carbon, ammonia, nitrate and phosphate reducers Measures 16-inch length by 7-inch width