Five foot hanger/roller assembly too long, grommets too wide at 18". Revised the cotton duck door hanger/roller, using 5 - 4 foot lengths of 1-1/2" 14 gauge slotted angle (Lowes 69815 ). 2" strap hinges welded to angle pieces.[Hinges were later found to promote twisting of the supports and were cut away from the hangers]. Roller hanger 1/2" threaded rods bolted to center of 4' angle canvas hanger span. Used a gallon of Latex roof seal and plastic mesh for a double layered seal around roof vent. Wired 240 AC outlet to panel board.