iSpring FP25B 20"x4.5" Universal Sediment Filter Cartridges, Multi-Layer Gradient Design, NSF Certified, White, 20 x 4.5 Inch-5 Micron / 1 Pack

• Patented 4-layer Gradient Melt-Blown Polypropylene, up to 3 times more efficient
• 20" (Length) x 4.5" (O.D), Universal replacement for industry standard 20" Big Blue filter cartridges
• 5-micron rating, NSF certified, Individually Wrapped
• Coreless melt down construction without using any Surfactant, Adhesive or Binder. Physical strong and resistant to chemicals
• Based out of Atlanta, Georgia; (678) 261-7611

Usually used as the first stage for 20 in. whole house filters. It is effective in removing dirt, rust and sand particles down to 5 micron. Depending on the inlet water quality or flow rate, it needs to be replaced every 12 months or 100,000 Gal. of water.