The 3M Aqua-Pure AP Easy C-Cyst-FF Under Sink Full Flow Replacement Water Filter Cartridge is one of several options in a complete product portfolio for delivering cleaner, clearer drinking water. This replacement water filter cartridge is NSF listed to reduce particulate, chlorine taste and odor and parasitic protozoan cysts. From the Manufacturer The Aqua-Pure C-Cyst-FF water filter is a long, round filter with a long connector plug designed for Aqua-Puree's AP Easy Cyst-FF Replacement System and AP Easy Full Flow Drinking Water System.