We replaced ours with Sunbrella (70%?) shade material. I used the existing bolt holes to fasten aluminum channel around the perimeter, then used aluminum plates to clamp it into place. It is very adjustable. The Sunbrella material promotes more airflow. This is very nice during warm nights. During cold nights we drop the top and crack the windows
(two side and the door). This material is unique in that you can see out but you can't see in during the day.