These were great while they lasted.  As others have said, they do eventually split open up the back.  I tried fixing with duct tape, but to no avail.  So, enjoy these while they last.  For me, they lasted for two years, and I'm OK with that.  The bottom cushion also came loose, moved around, and bunched up over time.  I threw it out.  I continued to wear them without the insert and I had no problems (but I don't have picky feet).