Water Inc. HousePure Secure Replacement Cartridge 1.50CHousePure Secure LEVEL 2 Replacement Cartridge for Tankless Water Heater Scale PreventionReplacement cartridge for HousePure Secure 1-1/2" tankless water heater filter system providesvannual protection against costly water heater scaling and sediment build-up.Filter Capacity: One year or when gauge indicates change is neededMax Flow Rate: 20 gallons/minuteIncludes a filter change indicatorTested to NSF/ANSI Standard 42 for material requirements