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Now, install the horizontal track. Slide the horizontal track over the roller. Attach the curved end of the track to the flag bracket using the supplied track bolts and flange nuts, ensuring the head of the bolt is on the inside of the track. Secure the end of the horizontal angle to the top of the flag bracket with a carriage bolt. Then, attach the opposite end of the horizontal track to the rear track hanger. In this example, an existing wooden structure was used as a hanger, but if you don't have one, rear track hanger kits are available. To ensure the horizontal track is perfectly square, measure diagonally from one corner of the track to the opposite diagonal side. Both diagonal measurements should be equal. Adjust the track's position if necessary to achieve squareness.