Abstract: A desiccant cartridge for use with a receiver/dryer of an automobile air conditioning system. The desiccant cartridge contains a cup member and a cap. The cap includes a plurality of fingers located about a periphery thereof. The fingers engage the cup member to secure the cap to the cup member. The fingers operate to facilitate insertion of the cap into the cup member using a one-way lock-type arrangement. Accordingly, pushing the cap downward into the open end of the cup member causes the fingers to deflect upward and slide along an interior surface of the cup member. Upward movement of the cap is limited by the fingers engaging the interior surface, which hold the cap member in place. Accordingly, the cap can be inserted into and locks in the cup member at any position.