APEC High Capacity Pre-Filter Set Is USA Made With Quick Connect Fittings For Easy Replacements. Includes (1) Sediment, (2) Coconut Shell Carbon, And (1) Dow Filmtec Membrane. High Performance Replacement Filters Compatible With All Standard Countertop RO Systems. Stage 1-2 Recommend changing every 6-8 months. Stage 3-4 Recommend changing every 2-3 years. APEC ULTIMATE Complete…