Multi-Action Replacement Cartridge 10″
10 micron activate carbon block filter which reduces scale, lime, rust, sand and other fine sediment. Perfect as a pre filter for the two-stage filter. Often combined with the 25 micron filter – Heavy Duty Replacement Cartridge.
Product Spec sheet can be found here Two-Stage Filter System – Large Installation Guide
More info can be found here https://www.youtube.com/watch?v=rfwZTcqHIgY&t=1s