CERTIFICATION: NENRENT Refrigerator filter tested and certified by NSF International against NSF/ANSI Standard 42 in model WQ-94G2. Advanced carbon block material could multiple purify the water IMPROVE THE TASTE: Recommend that replace filter every 6 months or 300 gallons,which comes first EASY INSTALLATION: No tools required. Installed easily with a positive lock (NO LEAKAGE) and high flow rate. These replacement filters are delicate design to perfectly fits the original. Manufactured by the NENRENT technologies