FIG. 1 is a top, front and left side perspective view of a refill head for a toothbrush according to an embodiment of the new design;
FIG. 2 is a bottom, rear and right side 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 an enlarged top plan view thereof;
FIG. 8 is an enlarged bottom plan view thereof;
FIG. 9 is a front perspective view of a refill head for a toothbrush according to a second embodiment of the new design;
FIG. 10 is a rear perspective view thereof;
FIG. 11 is a front view thereof;
FIG. 12 is a rear view thereof;
FIG. 13 is a left side view thereof;
FIG. 14 is a right side view thereof;
FIG. 15 is an enlarged top view thereof;
FIG. 16 is an enlarged bottom view thereof;
FIG. 17 is a front perspective view of a refill head for a toothbrush according to a third embodiment of the new design;
FIG. 18 is a rear perspective view thereof;
FIG. 19 is a front view thereof;
FIG. 20 is a rear view thereof;
FIG. 21 is a left side view thereof;
FIG. 22 is a right side view thereof;
FIG. 23 is an enlarged top view thereof;
FIG. 24 is an enlarged bottom view thereof;
FIG. 25 is a front perspective view of a refill head for a toothbrush according to a fourth embodiment of the new design;
FIG. 26 is a rear perspective view thereof;
FIG. 27 is a front view thereof;
FIG. 28 is a rear view thereof;
FIG. 29 is a left side view thereof;
FIG. 30 is a right side view thereof;
FIG. 31 is an enlarged top view thereof; and,
FIG. 32 is an enlarged bottom view thereof.
The dashed broken lines illustrate portions of the refill head for a toothbrush that form no part of the claimed design. The dot-dash broken lines define the bounds of the claimed design and form no part thereof.