The ornamental design for a curbbit with plasticmouthpiece, as shown and described.
FIG. 1 is a top right rear perspecitve view of a curb bit with plastic
mouthpiece showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left elevational view thereof; and,
FIG. 4 is a bottom plan view thereof.
A rear elevational view is identical to the front elevational view of FIG.
2. A right elevational view is identical to the left elevational view of
FIG. 3.