FIG. 1 is a perspective view of a seat base showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a side view thereof; and,
FIG. 6 is another perspective view shown with environmental structure.
The broken lines showing of a seat and wheels in FIG. 6 are for illustrative purposes only and form no part of the claimed design.