The tank mesh bags are easy to fill and empty with zipper design to keep filter media secure. The bag is provided with high-quality plastic zipper, salt resistant and . It is very convenient to clean and maintain at ordinary times. When the filter material is put into the bag,Then put it into the filter tank and replace it or clean it directly. Filter bags provide excellent mechanical filtration, which helps reduce the amount of ammonia-producing organic matter in your aquarium by trapping debris which also helps prevent large and small object like sand and coral from damaging aquarium equipment. Nylon has poor dyeing property, but its color fastness is good, so it is not easy to stain, not easy to fade, and easy to clean. The mesh media bags fit perfectly in a variety of filters including canister filters, power filters, sumps, wet/dry filters and pond filters. Specification: Material: Nylon White Large Hole/White Small Hole Size(LxW): Approx.15x20cm/5.91x7.87inch White Small Hole Size(LxW): Approx.41x33cm/16.14x12.99inch Black Small Hole Size(LxW): Approx.31x27cm/12.2x10.63inch Package Includes: 10 Piece Aquarium Filter Bag Note: Since the size above is measured by hand, the size of the actual item could be slightly different from the size above. Due to the lighting effects, monitor settings, etc. There could be some slight difference in the color of the pictures and the actual item.