HAYWARD PROGRID DE FILTERS DE2420, DE3620, DE4820, DE6020 and DE7220 Pro-Grid™ vertical grid D.E. filters provide superior water clarity, efficient flow and large cleaning capacity for pools and spas of all types and sizes. Constructed with high- strength PermaGlass XL™, Pro-Grid combines high-technology features and "service- ease" design for an unparalleled filtration value for both new pool and aftermarket installations. In addition, Pro-Grid delivers low maintenance and dependable operation. Features include: High capacity, rapid release manual air relief valve bleeds air with a quick quarter turn of the lever Filter tanks made from durable glass reinforced copolymer to meet the demands of the toughest applications and environmental conditions, including in-floor cleaning systems Self-aligned tank top and bottom make access to servicing the grid elements fast and simple Heavy-duty, tamper-proof one-piece flange clamp securely fastens tank top and bottom. Allows quick access to all internal components without disturbing piping or connections High impact grid elements designed for up-flow filtration and top-down backwashing for maximum efficiency Uniform low-profile base make removal of grid nest fast and simple Inlet diffuser elbow distributes flow of unfiltered water evenly to all filter elements and provides even distribution of D.E. to grids Convenient valve and plumbing options allow for customized control 2" full-flow internal piping and plumbing for less resistance to flow and maximum performance 72 ft² filter allows for both commercial and large residential applications and years of non- corrosive, trouble-free performance