This first effort netted around 210 degrees F, not bad for a slapped-together project. I knew that I would probably need a reflector or two to goose up the temp. So I framed two cheap glass mirrors from Target,that hang from a hinge below the "window", about 22"x46". I put the frame on a folding table "leg" so that it would lay flat against the garage wall, and flap out at 90 degrees to send more sun into the cookbox. When installed, this boosted the temperature to a more respectable 260 degrees. The mirror is set to capture sun early in the day, without adjustment through the afternoon, since the 46" is parallel to the ground.