The ornamental design for an improved filtersupport, as shown and described.
FIG. 1 is a front perspective view of the improved filter support mounted on an exemplary filter in accordance with the present invention;
FIG. 2 is a front elevation thereof;
FIG. 3 is a rear elevation thereof;
FIG. 4 is a top elevation thereof, the bottom being a mirror image; and,
FIG. 5 is a side elevation thereof, the left and right side elevations being a mirror image of each other.
The broken lines depicted the drawings are directed to the environment and are for illustrative only; the broken lines form no part of the claimed design.