In the sixties thru the 70's they started making some of the models with windows like this in the lids. It was the "Gold Crown" models that had the window glasses, as I recall. I think it started with the rollermatic series for the home washers. The design of the grid is just that, a design. They just added to the cosmetic looks of the machine. After WCI took over, they continued putting the glass insert windows in the Gold Crown models for a while,but without the design in them. The windows were always a part of the coin op machines, from early on. The earlier coin op machines had round glass inserts and the later ones had the same square one you see in the picture. One interesting thing you might note is that the coin op machines made in the late 60's had the appearance of the rollermatic machines, but were actually a multimatic mechanism with the two belts. They also were rapidry 1000 machines. At least the ones I have seen were. I know that in the 70's they still had the solid tub coin op machines, but had the newer rollermatic mechanisms with the one belt like the home style units without the large perforated tub.