SpiroPure SP-WP1-20BB 20x4.5 Inch 1 Micron String-Wound Polypropylene Water Filter Cartridge Replacement for SWC-45-2001 WP1BB20P (Case of 6) - Perfect for Home, RV, and Commercial Water Filtration Systems

I haven't used one yet from this batch but have used this brand and it works fine. My biggest problem was because of the price I didn't change them often enough. These are such a great price that they will be changed more often. In addition, I bought another Big Blue and one will use a 5 micron then into a 1 micron filter from this same company. I have an older well with a lot of sediment and the 1 micron filter by itself made my water crystal clear.