ECP Series cartridges are manufactured from a special formulation of resin-impregnated cellulose and polyester fibers. This unique blend of materials provides a higher wet strength than regular cellulose cartridges. It also provides high flow rates and dirt holding capacity, while maintaining extremely low pressure drop. The media is pleated around a polypropylene core for added strength and the ends are immersed in a thermo-setting vinyl plastisol. Embedding and sealing each end of the pleat block in this fashion fuses the components together forming a unified end cap and gasket. ECP Series cartridge end caps feature a color-coding system for easy identification of micron ratings: Tan (1-micron), White (5-micron), Blue (20-micron), Yellow (50- micron). The new ECP cartridges contain more media surface area than most competitive cartridges. The big blue 20" ECP cartridges contain 36 sqft of media. Micron Rating (nominal) Dimensions Model Pressure Drop 20 4-1/2"x20" ECP5-20BB 1 psi @ 10 GPM Materials of Construction: Media: Cellulose Polyester Core: Polypropylene End Caps: Vinyl Plastisol Temperature Rating: 40ºF to 125ºF (4.4ºC to 51.7ºC)