I've worn Birkenstocks for years and love them.  After wearing this pair for 30 minutes, both shoes developed an annoying squeak.  After the 2nd day of embarrasing squeaks with every step, I'm putting them on the shelf for awhile.  I contacted the company and they suggested baby powder or leather conditioner/oil near the straps.  I'll give it a try, but right now, I'm just extremely disappointed.