M MANN FILTER

FILTERS FOR GAS DEVELOPING MATERIALS AND FLUIDS-NAMELY, FOR AIR, GASES, FUELS, COMBUSTIBLE MATERIALS AND OILS, FILTER INSERTS, COMPRISING POROUS MATERIALS-NAMELY, PAPER, PULP-BOARDS, [ ASBESTOS, ] FELT, SILICEOUS, CERAMIC MATERIALS, ALSO AS METALLIC, NATURAL AND SYNTHETIC FIBER, WEBS, FABRICS AND KNITTINGS, AND THEIR PARTS