Quality.  I am trying to cover a really bad peel and stick mirror job 3x4 of 12^2 mirrors, all crooked.  The wall is not quality so peeling them off would be a disaster.  This is the right size for the right price.  Took a long time to find.  I am going to add crown molding around it as a frame because it's the exact same size as those hideous mirrors so need a little wiggle room.