Hayward C5030 SwimClear 525-Square-Foot Large-Capacity Cartridge Pool Filter Quad-cluster of high-quality polyester cartridge elements provide 225, 325, 425 or 525-square feet of filter area for extra dirt-holding capacity 2-Inch full-flow internal piping and plumbing for less resistance to flow and maximum performance; allows quick access to all internal components Pvc union coupling connection accepts 1 1/2-inch or 2-inch piping for plumbing versatility; 2-inch recommended Full size 1 1/2-inch integral drain allows for fast, 100-percent clean-out and easier flushing of tank Heavy-duty, tamper-proof, one-piece clamp securely fastens tank top and bottom