Absolute micron retention ratings: 0.05 to 0.45 m. Available with PES, Nylon, PCTE, Polyproylene and PTFE membranes. Available with PES, Nylon, PCTE, Polyproylene and PTFE membranes. XPleat* pleated membrane filters – a low-cost line of pleated cartridge filters that uses either PES membrane or dual rated glass microfiber filter.