20-Inch Water Resin Softening Filter Cartridge Reduce Hardness And Effectively Removes Descaling RESIN Water Purifier Filter. Resin filter,a reversible chemical reaction between ions water and solid ion, when some of the ionic liquid is ion exchange solid like will be ion exchange adsorption, in order to maintain electroneutrality of the solution. Therefore, the ion exchange solid must release equivalent ion in the solution, thereby softening water scale.
inner diameter :28mm
outer diameter :70mm