Size Selection Guide For inside mount, ensure your window frame depth is at least 3" and blackout shades should be the same size or slightly smaller than your window width (for 35" window width, select 35" or slightly smaller). For outside mount, blackout blinds should be at least 4 inches wider than window width (for 35" window width, select 39"shades). Note: Fabric width is 0.8" narrower than the shade size. Safe & Innovative Design Our cordless design is safer for kids and pets. You can easily adjust window blinds for home to any height between 0-75 inches. Featuring a built-in tension adjustment system on the right end of the top bar.