Big Brand Water Filter, Inc. manufactures Ultra-Pleat standard-size filters to fit the four popular sized filter housings; 10" & 20" slimline and 10" & 20" Big Blue filter housings. Each Ultra-Pleat� Cartridge is a highly electropositive filter that rapidly adsorbs particles, no matter how small. The Ultra-Pleat media has a high capacity for particles as large as tens of microns or as small as a few nanometers. The active component in Big Brand Water Filter, Inc. patented Ultra-Pleat� filter media is a microfiber two nanometers in diameter. The nano fiber contains a naturally occurring and highly electropositive charge. As such it will attract and retain particles, no matter how small. These nano fibers are dispersed throughout a microglass fiber matrix resulting in a non-woven media with 2 micron average pore size and with water flux typical of that pore size. This technology was developed in conjunction with NASA and is used in military applications for protection from biological warfare. Big Brand Water Filter has made a special arrangement to purchase military grade nanofiber media. We then have the filters custom made to our specifications. This product is exclusive to Big Brand Water Filter, Inc. and isn't available from any other water treatment dealer.