*Pack of (10) Short 4" Filter Socks, 200 Micron Bags, 8-1/2" Long, Made in the USA
This is for nine (9) 4 inch Filter Socks (200 micron-8.5" long).  Polyester Felt, Sewn Construction, Glazed Finish, with 4" ring.   Made by Peco-Facet (formerly Purolator), Div of  CLARCOR Company.   CLARCOR is the most diverse filter company in the world. http://www.clarcor.com/.  Very high quality material.   Filter socks are the most convenient form of mechanical filtration. They remove excess food, detritus, organic waste, dust, and other particulates. Removing these particulates from the water column will reduce the amount of organic matter that produces ammonia and other undesirable substances in the aquarium. Filter socks also help prevent larger objects, such as sand, crabs, snails, etc. from damaging pump motors. Regular filter sock use will lower organic levels and result in CRYSTAL CLEAR WATER!