APEC ESSENCE series standard capacity pre-filter set for ROES-PH75 is made with high quality filtration components to protect and prolong the lifespan of your reverse osmosis system. Premium quality filter set lasts over 6 to 12 months for high performance impurity removal. These standard size filters are 10 inch and compatible with all standard size under counter RO systems. 1st stage: 5 micron polypropylene filter to remove sediment, particles, and rust. Prevent sediment from building up and clogging the filters and the system. 2nd and 3rd stage: 10 micron extruded carbon block filter to remove chlorine, taste & odor at a fast flow rate. Improve water taste, protect the life of the RO membrane and enjoy chlorine free water. 6th stage: 10 inch high purity pH+ calcium carbonate alkaline inline filters W/quick connect. Compatible with APEC ROES-PH75 and all other standard size under counter reverse osmosis systems. For over 20 years, APEC has been an industry leading manufacturer who specializes in high performance RO systems. As the original manufacturer, we have dedicated a knowledgeable and sincere team that is committed to providing customer SATISFACTION in hopes to bring many years of enjoyment and good health for you and your family.