An Outside Mount is when the blind is mounted up above the window, on the wall, or on the window trim. This is typically done in two situations. If there are obstructions inside your window frame, or if your frame lacks sufficient mounting depth for an Inside Mount. You may also consider an Outside Mount if your windows are an uneven shape or size or if you prefer that the window trim not show at all. With an Outside Mount, you give us the exact measurement of the blind, not the window. The factory will make it to your exact specifications.