AP814 Aqua-Pure & Pentek WP5BB97P, WPX5BB97P, WP5BB975 Compatible Polypropylene String Wound Water Filter Cartridge by KleenWater, 5 Micron KleenWater KW4510SW - 5 micron 4.5 X 10 inch string wound water filter cartridge Compatible in all large diameter and "Big Blue" style water filters Made in the USA. High quality - low cost! 20 gallon per minute flow rate Replace cartridge every 6 months or upon substantial pressure reduction