*Click "See More" for Measuring Instructions* This product is cordless, child and pet-safe, and certified per WMCA's "Best for Kids Program". The blackout fabric is 100% woven polyester with a 3-pass coated backside which gives 100% blocking of light through the fabric and provides thermal insulation. Attractive-looking fabrics are of the highest quality which gives you custom quality without the custom price. How to choose the right size for mounting inside the window frame: measure horizontally, along the top of your interior window frame. Round down to the nearest. How to choose the right size for mounting outside the window frame: measure horizontally, along the top of your window moulding. Round down to the nearest. For optimal coverage, order or more than the width of the window frame. *Please take note that the fabric panel is always smaller than the final blind size that you order.