Described are filter cartridges having an inlet opening and an outlet opening on the stem of the filter cartridges, which permit the permit the entry and exit, respectively, of a fluid in one or more radial directions perpendicular to the longitudinal axis of the stem. The hub includes an inner rim portion having the spindle opening at its center and an outer rim portion connected to an outer side of the inner rim portion for extending from the inner rim portion via a step difference towards the side of insertion in the spindle opening. Paging control elements are displayed according to either the binary subdivision approach or the serial progressive approach in dependence on a determination as to which approach is more advantageous based at least in part on factors such as, for example, total number of pages, current page location, distance to end points, screen size, etc.