The panel's fit depends on you providing accurate dimensions of your opening. Please measure your opening following these instructions and referring to the above illustrations. Enter the dims in the boxes corresponding to the drawing. Enter fractions like this: 2 1/2 etc.
We need the width - W, height- H, and peak - P height (if arched) of the opening. This are the "clear opening" dimensions. We also need Dim R and Dim D where the panel sets into the frame. If you have any confusion about measuring, contact us.