SpiroPure SP-EC20-20 20x2.5" 20 Micron Pleated Cellulose Sediment Water Filter Cartridge (Case of 20) - Perfect for Whole House Water Filtration, Well Water Systems & Commercial Applications

These are far superior to the ones we were purchasing from the water softener company. Our old ones were lasting 1 months each. We have heavy iron, magnesium and calcium in our water and this one has been in 4 months and still doesn't need changes. It's filtering is far superior to what we've been using.