The filter material is food-grade ion exchange resin that reduces salts. It can be placed in all filters above or below the counter. It is usually combined with an activated carbon filter. 

Ideal for areas with high salt content. If your area has a serious salt problem (e.g., if you live permanently on an island), you should change the filter frequently.

The ion exchange resin swaps Magnesium and Calcium ions, i.e., salts, with sodium ions. Sodium ions, compared to magnesium and calcium, are much easier to dissolve. In large salt reduction systems, the resin "regenerates" if we add special salt, to refill it with sodium ions. In smaller systems, such as household water filters above and below the counter, we simply replace it with a new resin filter cartridge.