Backrest

FIG. 1 is a perspective view of a backrest showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a right-side elevational view thereof;

FIG. 5 is a left-side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is another perspective view illustrating the backrest on a chair thereof.

The broken lines in the drawings depict part of the backrest that form no part of the claimed design.