【CERTIFIED AND TESTED】: Tested and certified by NSF International against NSF/ANSI Standard 42 for the absorption of chlorine taste and odor and particulate. 【REPLACEMENT CYCLE】: To achieve optimal performance, change your filter every 6 months or 300 gallons and the replacement requires no tools to replace the filter. 【PREMIUM MATERIAL】: Uses high-grade natural coconut shell activated carbon block as filtration material, which features better adsorptive ability and better filtration performance with microscopic pores.