Below you will find each of the systems we offer and the corresponding length and width of each system. When you see the “68” and “75” in the second column, this is referring to the length of the panel used in that system. This changes the spacing requirements when installing the system. Please keep in mind that the system should not be install over a forward sloping portion of your roof, the base brackets of the system (feet) are 4 inches wide and 20 inches long and cannot be installed on top of fiberglass front/end caps or shower domes, the feet will be installed just above the sidewalls, and the center points of those feet should not be placed where there is an AC unit (if possible).