Aries (AF-20-4202) 20"x2.5" Twin Bed Mixed Bed DI FilterAries Filter Works Aries AF 20 4202 20"x2. 5" Twin Bed Mixed Bed DI Filter Lab grade deionization in a standard 20 inch cartridge. For applications that demand near zero TDS and ultra pure water. Twin Bed DI Resin 20" x 2. 5" TDS Reduction WHY IT WORKS Mixed bed deionization removes dissolved solids that carbon and sediment filters miss Twin Bed DI Resin Separate cation and anion resins work together to strip dissolved minerals, producing water with