3 Filter Set for 4-stage Countertop RO Systems, including 5M Sediment, T28 GAC and DI bed 0PPM filters for aquariums, made in USA Universal 3 Filter Set for 4-stage Portable Reverse Osmosis RO, made in USA Fit Reverse Osmosis Revolution Systems (Aquarium) Fit most of portable (countertop) Reverse Osmosis Systems with 1/4" connection If you are not sure about compatibility, please, contact our Customer Care Ideal for Aquariums