Don't get me wrong, the shelves ended up working perfectly BUT the predrilled holes in them are spaced for studs that are 16" apart (which is standard in most homes).  Turns out the studs in my home are 24" apart (also very common).  I wanted to ensure the shelves were very sturdy so I had to drill another hole into the shelf to adjust for the stud distance. 

It was crazy inconvenient but I'm really happy with the finished product. I love how sleek they look.  You can't see the hardware at all when it's in the wall which is exactly what I was going for.