Please read the following information about sizing your cordless cellular shade in the following bulletpoints. Your shade will arrive in the exact size that you order.For INSIDE MOUNT: Measure your window horizontally with a steel tape measure in three places; top, middle and bottom, use the smallest measurement, rounding down to the nearest ¼ inch then round down to the nearest whole inch. This will ensure raising and lowering the shade in the window frame. For example, if the smallest measurement is 36 1/2 inches, then you should order 36 inches as the width. The size you order is the size you will recieve.For OUTSIDE MOUNT: Measure your window horizontally with a steel tape measure in three places; top, middle and bottom. Using the LARGEST measurement, add 2 to 4 inches and order this width. This will allow for an overlap on each side of the window to provide privacy. You may want to add to the height for overlap as well. For example, if the largest width measurement is 36 inches, we suggest ordering 40 inches as the width. The size you order is the size you will recieve.Each Linen Avenue Cellular Shade has a SMOOTH CORDLESS operation. HARDWARE: End caps, simple snap-in top mount brackets, and mounting hardware is included. Headrail size: 1 5/8 High and 1 7/8 Deep (2 3/16” Deep with bracket).If you need additional help measuring or installing you cellular shades, watch our "How to Measure and Order" and "How to Install" videos or feel free to contact us. Please click on our Linen Avenue store front to view our full catalog.