I have been wearing Reef's flip flops for years.  Before I use to be able to only walk for about a 1/2 hour and my lower back would begin to pain.  With Reef's I can walk for literally hours at a time before my feet or back start to hurt. I always buy the ones for good arch support.  Now for the last couple of years I also buy them for my 6 year old granddaughter and she loves them.