Pentek - DGD Series 20" x 4.5" Big Blue Dual-Gradient Density Polypropylene Sediment FilterThe Pentek DGD Series 20" x 4. 5" dual gradient sediment filter delivers up to three times the dirt holding capacity of standard spun or wound cartridges by combining two gradient density layers in a single 100% pure polypropylene construction. Available in three dual gradient configurations (25 1, 50 5, and 75 25 micron), it fits all standard Big Blue 20" housings and handles flow rates up to 20 GPM with minimal pressure drop. SPECIFICATIONS Pentek