I have a Greyhawk 29MV. I used cardboard to make a template for a screen frame. My exit window is curved on the bottom so it doesn't have four right angles. I transferred the cardboard template unto a Masonite board and used a jigsaw to make a 1 1/2" frame. I stapled screening and Velcro to one side of the frame. The matching Velcro with a sticky side was attached to the frame of the exit window on the inside. I use a paint stick cut to length and a small bungee cord to hold the window open. I previously tried to find frame material that was curved or that could be bent to fit my exit window but had no luck. If your exit window has four right angles, you can find framing material online or at HD or Lowes. If your exit window has two curves, you will most likely have to construct the frame yourself. Good luck!