The Cypress HF-31 Replacement Composite Plus Filter reduces fine particulate materials such as sand, dirt, and rust from the water supply. This is the Stage 1 replacement filter for the H2O+ Cypress H630 Countertop System. It acts as a sediment prefilter to protects and extends the life of the other filters. Quick connect for easy filter replacement. Tested and certified by WQA. Recommended replacement every 6 months.