This HYDRONIX SPC-45-1001 pleated polyester filter has a particle retention size of 1 micron, and is used in a water filtration system. It has an outside diameter of 4.5 in. and overall length of 9-3/4 in. It has a non-woven polyester body for resistance to chemicals and bacteria, a polypropylene core, and vinyl plastisol end caps. This filter is washable and reusable and can withstand temperatures ranging from 40°F to 125°F. This pleated polyester filter is suitable for a variety of residential and commercial water filtration applications. Water filters remove undesirable particles, chemicals, and microorganisms from water by means of a semipermeable barrier, adsorption, or biological processes. They are made of densely packed synthetic or natural fibers that trap suspended particles, materials that block microbes or adsorb unwanted chemicals, or substances that cause a chemical change, such as acid neutralization. For most residential, commercial, and industrial applications, water filters are manufactured in the form of replaceable cartridges that fit inside permanent housings. Filtration systems typically consist of a series of 2 or more types of filters, each designed to remove different contaminants.