FIG. 1 is a rear left perspective view of the present new design for a sprinkler base configured to include an exemplary sprinkler head which is illustrated in dashed lines and forms no part of the claimed design;
FIG. 2 is a rear left perspective view of the present new design for a sprinkler base;
FIG. 3 is a top plan view thereof;
FIG. 4 is a right elevational view thereof, the left elevational view being a mirror image thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a front elevational view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing various features of a sprinkler base are for illustrative purposes only and form no part of the claimed design.