It is a filter bag with a filtering precision of 100 microns & is more suitable for filtering particles of smaller diameter, so the fish tank is kept clear and bright for a long time. It is suitable for purification of planted aquarium tank , coral aquarium, sea water tank aquaculture and ornamental fish tank It has ability to keep impurities and microorganisms trapped in the filter bag for long period of time. Instantly improve your water quality with our pre-rinsed 100 micron filter socks. These highly durable mechanical filters help trap uneaten food, free floating particulate matter, micro-bubbles, and even dust from your aquarium. Pre-molded with internal plastic handles for easy servicing and double stitched for maximum reliability, micron socks are truly the BEST upgrade to your filter/sump for polishing water. It results into a CLEANER & CLEARER aquarium!