The back windows are busted out and I really don't want to special order these $$. So I bought the smallest ones they had at Lowes $40 each is my kinda price! Installing them on a curved bus is a bit tricky though, I used 1x2s to bridge the gap between window and curved metal. I still need to add the curved side support frame. I am going to make a small template and use 4x1 or 6x1 along the curve and a 2x4 going vertically on the side, then fill gaps with foam and trim it out. I also intend to build a shelf directly under the window so you will not see the metal bracket sticking out in the picture.