APEC Water Systems FILTER-SET-CTOP US Made Double Capacity Replacement Filter Set For Ultimate Series Countertop Reverse Osmosis Water Filter System Stage 1-2 APEC Water ULTIMATE Series FILTER-SET-CTOP is for RO-CTOP, and RO-CTOP-PH Includes sediment & coconut shell carbon filter to protect and prolong the lifespan of your RO 1st stage sediment filter to remove dust, particles, and rust 2nd stage coconut shell carbon filter to remove chlorine, tastes, odors, cloudiness and colors High performance replacement filters are compatible with all standard countertop RO systems