Disposable air filter

Claim 1

A filter system for removing particulate and dirt from the airflow of: heaters and air conditioners comprising: a primary filter and a secondary filter releasably secured thereto and in axial alignment therewith, said secondary filter being the first impact surface of dirty air, such that the airflow passes first through the secondary filter and then through primary filter wherein the primary filter comprises a conventional generally rectangular frame formed from suitably cut and scored cardstock comprising a plurality of interconnected from members, each of which is generally U shaped in cross-section, said frame carrying a sandwich of a metallic layer adapted to pass air therethrough and wherein the secondary filter comprises a generally rectangular thin sheet of filter medium sized substantially the same as the frame of the primary filter, said secondary filter being superposed upon said primary filter, said secondary filter medium being adapted to remove dirt and particulates from an airflow, said secondary filter having a pressure sensitive removable adhesive layer on one side thereof, said adhesive being capable of releasibly binding said sheet to the outside of the frame of the primary filter.