Notes on measuring and installation: Measure every window, even though they appear to be alike. Convert to inches. Remember to allow extra space for drapes when drawn back if you wish to fully expose the window. If you wish to have an under-treatment which will be recessed inside the window frame, two inside Mounts require a rod 1/2" less than the width of the sash measurement. We recommend additional brackets every 5' to 7' to support the weight of your treatment, and 4 rings per foot, roughly. Single Rods more than 105" are subject to higher freight costs. For long spans, a splice - slipped inside the rod - will be hidden by the required center bracket.