At most I can give this 2 stars. It kind of worked for awhile but it smelled horrible day 1.  The smell stayed with the sandals for awhile even after the stuff dried. Not to long after purchasing in 2013, the bristles fell off or dissolved into the bottle. I want to use it again today and it seemed to smell worse. It truly smells like vomit - at least the bottle I have did. I have decided to purchase the Birkenstock cork sealer and chalk this up to one of life's lessons - penny wise and pound foolish.