I used clear table cloth.. cuts vision like crazy.. seems very see throw when something is pressed up to it ( touching) but trying to see more than 5 feet away is nearly impossible.. i used it for 1 winter.. i cut to the shape of opening then used velco tape( sticky) on one side to attatch to the roll cage and the door.. come summer i pealed it all off and used GOO GONE to remove the glue from the velcro..

 

Also go to my thread called build on a budget and scroll close to the end.. you will see 3 pictures of my new designed upper doors. I built metal frames attached black puckboard to it and drilled out a few hundred holes(like heavy duty window screen) i have since then bought 1/16" clear plastic sheeting called clear view its like looking through glass.. i cut that to the shape of my upper panels and attached that to the inside of the puckboard for winter riding to block out cold air.. come summer time it can be removed and the black puckboard with holes allows air flow to stay cool but also protects me from mud and sticks/branches slapping in

 

Thank you! I will look for it. Any chance you have pictures to share in case I can't find it? Going to look right now.