Will not know if they work for the purpose I purchased them (to keep sun from damaging the curtains) until after one summer is over.  Pleased with the ease of attaching them, however.  I was able to use one liner for two curtains by cutting them in half and hemming the sides.  Also had to cut shorter and re-hem.  Easy to do this with a fairly decent sewing machine.  I did a lot of research before purchasing three of these liners, and felt that the description was well-written.  However, it would have helped to see on-line how to attach to curtain hooks.