The ornamental design for a “brush head,” as shown and described.
FIG. 1 is a perspective view of brush head showing our new design;
FIG. 2 is a left side elevation view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken line showing of bristle tufts is included for the purpose of illustrating portions of the brush head that form no part of the claimed design.