The special class of micro-glass and other fibers used in Z media are manufactured with utmost precision, to specific thicknesses and densities, and bonded with select resins to create material with extra fine passages. No other filter media can provide the benefits of Schroeder's Excellement® Z media: maximum dirt-holding capacity, superior particle capture, excellent beta stability, minimum pressure drop, high flow rate and low operating cost. The typical multiple layer construction has evolved from comprehensive laboratory testing to provide extended element life and system protection. Each successive layer performs a distinct and necessary function. The outermost layer is designed to maintain element integrity. Beyond this layer is a spun bonded scrim, offering coarse filtration and protection for the filtering layers within. Multiple sheets of fine filtering media follow, providing intricate passageways for the entrapment of dirt particles. Together, the various layers of filter media provide the ideal combination for peak filtration performance Schroeder NZ25 Filter Cartridge for NF30, Z-Media: Micro-Glass, 5.25" Cartridge Height, 1.75" Cartridge OD, 0.8" Cartridge ID; 25 Micron (absolute); Removes: Rust, Metallic Debris, Fibers, Dirt.