I recently moved into an old house that has an unfinished glass block window in the kitchen out to the porch. The unfinished area is about 12 & 1/2 inches square and it's in the center of the window. In another area of the house is a glass block window with a "vent" the same size. However, the glass blocks are 4 inches deep and I am told that size is outdated and hard to find. Where can I get a 12 x 12 vent for this window that is 4 inches deep?