US D441449 S1
FIG. 1 is a rear perspective view of an air flow filter for use in testing or treatment of the respiratory function of patients, showing my new design;
FIG. 2 is a front perspective view thereof;
FIG. 3 is a side elevation view thereof, the opposite side elevation being identical;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a top plan view thereof, the bottom plan view being identical; and,
FIG. 6 is a rear elevation view thereof.