text: Now that I know, the line in the base to line up the number of the roof pitch was near impossible for me to see with my not to good site. Now I found it after I finished 95% of the install process. All was great, except for that detail. It works just great, I'm sure it will help with the heat buildup. Please make a better mark in the base. I will probably never install another for the rest of my life. This was my first. I'm 65.