Replacement filter set for 6 Stage Heavy Duty Reverse Osmosis Revolution Countertop RO Total filters: 5 1st stage: Inline Sediment Filter 2"x10" 5 Micron, Made in Taiwan. 2nd stage: Inline Granular Activated Carbon T28 Carbon Pre-Filter 2"x10", NSF Certified, made in USA. 4th stage: Inline K5654BB Water Softener 12"x2.5". Made in USA. 5th stage: Inline Omnipure K2567-BB KDF-55/T33 (replaced old DI/T33 filter). & 6th stage: 3-in-1 Alkaline (raise pH level), ORP and Tourmaline in-line filter