Portable countertop alkaline mineral reverse osmosis replacement filter cartridges. This pack contains 2 x K2540 omnipure inline carbon filters for your annual 12 monthly filter change and the option of 1 x 9 inch PI Biopure alkaline mineral cartridge and 2 x K2540 filters for your annual 24 monthly filter change as recommended. If you require a membrane (recommended every 4 – 5 years) please use the options box provided to add to cart. All filters are NSF certified. Free postage Australia Wide.