Seachem 4in 200 Micron Filter Socks are a critical component in maintaining water quality in aquariums. They remove suspended debris and detritus, which often lead to excess dissolved organics, nitrate, and phosphate when left unchecked. This makes Seachem Filter Socks an integral addition to any sump and overflow system. In addition to a 200 micron rating for exceptional particulate removal, they feature welded seams, which, unlike threaded seams of similar products, will not breakdown over time. They have a singed finish, which reduces wear and prevents release of fibers back into the water column. Finally, the plastic collar simplifies installation and easily fits standard sump fittings.