11 air filters; electrical fans; [ gas-fired heating apparatus and structural parts therefore, all for use in rooms, buildings, parts of buildings, warehouses, halls, plants, tents, outdoor areas, and construction sites; ] oil-powered heating apparatus and structural parts therefore, all for use in rooms, buildings, parts of buildings, warehouses, halls, plants, tents, outdoor areas, and construction sites; electrical heating apparatus and structural parts therefore, all for use in rooms, buildings, parts of buildings, warehouses, halls, plants, tents, outdoor areas, and construction sites; and dehumidifying and drying apparatus, namely, dehumidifiers and dryers for heating, dehumidifying, and drying of rooms, buildings, parts of buildings, warehouses, halls, plants, and insulation layers of floors, and structural parts therefore