If i am remembering correctly we used 1" butyl tape. I would buy white because if a little squeezes out it will match the side of the RV. On our first HiLo we had to double up the tape so it would sit flatter against the siding. Search the internet for the best price. Measure all the exterior of your windows so you will know how many feet to buy. It is good to carry extra butyl tape,externa bond tape,screws and RV specific hardware and screws. Can't forget duct tape. Play some favorite music to make the job ,more pleasant. Use a helper as you steady the window out and on plywood/sawhorses. UTube has a tutorial on how this repair is done.