A filter assembly comprises a filter housing (23) into which a filter element is insertable. A core element (38) is provided extending within the housing (23). The filter assembly comprises a coupling assembly (200) that is insertable into the housing (23), the coupling assembly (200) comprising a leaf spring (201) having a span larger than an internal diameter of the filter housing (23), such that when the leaf spring (201) is inserted into the filter housing (23) the outer edge of the leaf spring (201) engages an inner surface of the filter housing (23) and the leaf spring (201) bulges in the direction of insertion of the leaf spring into the housing, preventing removal of the leaf spring, in a direction opposite to the insertion direction, from the filter housing (23), the coupling assembly (200) comprising a connecting part for connecting the core element (38) to the coupling assembly (200).