FIG. 1 is a front elevational view of a filter unit illustrating our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a side elevational view of a modified form of FIG. 1;

FIG. 7 is a side elevational view of a second modified form of FIG. 1;

FIG. 8 is a front elevational view of FIG. 6; and

FIG. 9 is a front elevational view of FIG. 7.

The top and bottom views of FIGS. 6 and 7 are identical to that shown in FIGS. 1-5 with the outlet port eliminated.