The ornamental design for a protective coverdesign for the back support portion of a chair, as shown and described.
FIG. 1 is a perspective view of the protective cover design for the back support portion of a chair of this invention shown attached to a chair. The chair shown in dashed lines forms no part of the claimed design.
FIG. 2 is a perspective elevated view of the protective cover design for the back support portion of a chair of FIG. 1 separated from the chair.
FIG. 3 is a front view of the protective cover design for the back support portion of a chair of FIG. 2.
FIG. 4 is a side elevational view of the protective cover design for the back support portion of a chair of FIG. 2 showing one side with the other side being the same; and,
FIG. 5 is a back view of the protective cover design for the back support portion of a chair of FIG. 2.