Also, the zipper does not zip all the way down the sides, so another frustrating design flaw making it difficult to add books & lunch-bag. The bubbles are NOT an indication of cleaning power or effectiveness, we think that it is because of very effective advertising campains back in the 1940s. If you are shopping open back headsets though, youre prob already in a pretty quiet environment. They fit true to their size, wide enough for my feet and are extremely comfortable. They are GREAT! Ease of installation, solid construction, simple compact design and to me most important, wide (for a 29" cruiser tire), properly angled hangers. Im a bigger woman, hard on shoes; this shoe can take it. Some were broken. ? Es de los más caros. I would definitely say that it lasted at least a good five hours, maybe even a little more than that.