This "trick of the trade" results in a professional, custom pillow fit that will make whatever insert you use look its very best. When laid flat, my pillow covers appears to have gently curved sides that will straighten out when filled with an insert. This feature is often requested by interior designers because it corrects a pillow insert's tendency to be understuffed at the corners by making the corners more form-fitting. Imagine putting a rounded object in a square bag. It will not fit as well as a bag that is contoured. It may be a bit surprising, but for the finished pillow to look square, its cover cannot be made perfectly square. You can often identify pillows missing this professional feature by their droopy dog-eared or long pointy corners. The more rounded your insert, the greater the distortion. Take a look at the photos below and check out the difference!Making pillow covers this way takes more time and care, but the result is absolutely worth it! Because of the contoured shaping, all measurements are taken across the middle of the cover and not from corner to corner.