This is not working. the wind is blowing and this is so light that it blows off. It is 160' which seems to be the best I can sustain. I have tried two boxes with paper between. I am trying a cooler with cardboard painted black inside now. I had glass on the first one, when it got to 220' the glass cracked. If the sun had stayed out, I think it would have cooked something, but the sun went behind storm clouds. This is a piece of plexiglass I had. I am trying it to see how it does.