Unicel UDH Series are pleated filter cartridges for residential, commercial and industrial pool and spa applications. Constructed of the highest quality non-woven polyester, with a durable polypropylene core to provide maximum strength they are washable, reusable and durable. The ends are immersed in thermosetting vinyl plastisol that seals the end of each pleat uniting the components and forming a permanently bonded end cap.