Looking for a refillable filter cartridge for 4x30" housings? This is it. These refillable cartridges fit the 4x30" housings from many different manufacturers and the Tucker® Mobile DI System. Fill with our virgin bulk DI resin to save big on your filter cost. Holds 1/5 of a cubic foot of DI resin Fits the H2Pro, 4060, and T-DI systems.