The replacement filter set for the Vertex Pure Water Machine Pt-4.0 Reverse Osmosis Systems includes:

Filter set includes:
(1) 5 Micron Sediment Cartridge Filter
(1) 10 Micron Carbon Block Cartridge Filter
(1) 10" Inline GAC Cartridge Filter (1/4" Female with 2-3/8" fittings and 2-1/4" Fittings) 

Set should be changed once per year. Membrane is not included in this Vertex Pure Water Machine replacement filter set. Change your membrane every 3 years.