Air flowing into the tank through the desiccant breather initially passes through the drying material (non-toxic ZR gel granules) and then through an air filter element (3 μm) to filter out the contained dirt particles. The condition of the drying material changes as the absorbed moisture increases and the colour changes gradually from red to orange. Orange drying material should be replaced. Options: adaptor plates, capacity indicators, replacement air filter elements, active charcoal drying material.