EASY TO FIT: Designed to fit the original with Twist and lock Design. No tools required. CERTIFIED QUALITY: All Aquafresh Filters are tested and certified by IAPMO to NSF Standard 42 for Structural Integrity, Materials Safety, Chlorine taste, odor reduction and System performance. Quality you can taste! HIGH EFFICIENCY FILTRATION: Activated carbon blocks certified to ensure contaminant reduction for 300 Gallons Or 6 Months, depending On Water Usage And Quality