Grooved Melt Blown Polypropylene Filter Features and Benefits Gradient Density, Multi-Layered, Melt Blown Sediment Filter Cartridge. Larger particles are trapped in the outer layers, smaller particles penetrate deeper. Greater dirt holding ability and longer life than non-layered cartridges. Thermally bonded polypropylene micro fibers for purity. No surface binders to reduce flow and increase change-out frequency. Available in wide range of lengths and micron ratings. Cartridges are individually shrink wrapped.