Determine if the shade or blind will mount outside the window frame onto the wall (Outside Mount) or if the shade or blind will be mounted inside the window frame (Inside Mount). Note: Most RV windows are Outside Mount.
Outside Mount - Measure the width (across) of the area to be covered. Example: End of frame to end of frame plus 2" added for additional coverage.
Inside Mount - Measure the exact opening size. The factory will make any necessary adjustments from your exact measurements to allow for inside clearance and ease of operation.
Measure the length (drop) of area to be covered. Example: Top of frame to bottom of frame with an additional 2" for mounting above and below window.