Chair base

FIG. 1 is a left side, top perspective view of a chair base, showing my new design;

FIG. 2 is a right side, bottom perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a right side elevation view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is another perspective view thereof, shown in a position of use.

The broken lines are shown for the purpose of illustrating both parts of the chair base as well as environmental subject matter. None of the broken lines form part of the claimed design.