I have a pair of these and the design is great  with the exception of the way they bottom section is attached to the top section.  the clips are good but the two sections do not remain straight and flip end to end.  I have even tried to staple the sections to keep them in position.  This would be the perfect design with a little engineering.  I will probably buy another pair and have one side sewn into place.  For me, they do not perform as advertised.