The Pentek P1 is a 1 micron spun bonded-polypropylene water filter cartridges designed to produce healthier, better-tasting drinking water. Manufactured from pure 100 polypropylene, the P1 is designed for purity and chemical compatibility. The spun fibers form a true gradient density from outer to inner surfaces and will not impart taste, odor or color to the liquid being filtered when used within the recommended temperature limit.br The P1's polypropylene construction provides superior chemical resistance and is not prone to bacterial attack. It can be used on chlorinated or non-chlorinated water supplies. The coreless strength of this water filter cartridge is achieved by sintering the many fibers into a solid matrix. It is tested and certified by NSF International to NSFANSI Standard 42 for material requirements only.