Combined seat and backrest unit for a chair
FIG. 1 is a perspective view of a combined seat and backrest unit for a chair showing my new design. 
     FIG. 2 is a perspective view of the same from a different viewpoint. 
     FIG. 3 is a front perspective view of the same looking from above. 
     FIG. 4 is a perspective view of the same from above and at one side. 
     FIG. 5 is a rear perspective view of the same looking down from above and on an enlarged scale with respect to FIGS. 1-4.