R-Series cartridges are manufactured from a durable, non-woven and reusable polyester fabric that is suitable for a wide range of filtration uses. The media is pleated around a polypropylene core for added strength, and the ends are immersed in a thermo-setting vinyl plastisol. Embedding and sealing each end of the pleated block in this fashion, fuses the three components together forming a unitized end cap and gasket. The overlap seam is sonically welded to reduce internal bypass improving filtration efficiency.The standard 9-3/4" length cartridge has more than four square feet of polyester fabric, while the larger Big Blue version has more than 16 square feet. The media is pleated to maximize dirt-holding capacity and extend the time period between changes or cleaning.R Series cartridges are resistant to both bacteria and chemical attack making them suitable for a variety of residential, commercial and industrial applications.