We are recommending these for use in aquariums and ponds, as a mechanical filter, but they can also be used in many other applications. These Filter socks provide crystal clear water Material: High Quality Nylon Bag , Plastic Ring Micron rating: Available in 50micron , 75micron ,100micron , 200micron , 300 micronand 400 micron Ring width: 7 Inches Length: 18 inches (Long) Package Quantity : 2 Pack Application : Chemical Industry Filtration of wine, beer,fruit juice, and edible oil Filter paint, paint,ink Aquarium,Water purification Kindly Tips:""Porosity"" is defined by nominal micron ratings (1, 5,10,25,50,75,100,200) indicating the largest particle that can pass through, in general, and reflecting an increase in the density. 1Micron mesh very small , 200Micron mesh more wider"