The measurement process was overly complicated - I understand the desire to get a tight fit into not perfectly square windwos, but a 17 page manual for something you can accomplish with math felt unnecessary. I also found the interface to be a bit challenging to work with when inputting fractions that necessarily had to be rounded but the system didn't like my entry. Otherwise, the inserts themselves fit well, very tight, noticeable noise reduction. I am so satisfied with them that I am considering placing another order (depending on whether I want to also spend the money to change window treatments).