I love this Fireplace Shelf Mantel! I wanted to ensure we had a perfect place for our family stockings and this delivered! 
Very easy to install. We added two Extra screw to both ends to ensure that it was not going anywhere. However, the instructions on there should be good enough. Remember to buy wood glue. I bought it just incase and it definitely is essential for a snug and sturdy mantel which was in the instructions as well.
The look was exactly what I envisioned. It was so light weight. We bought 70” and 6” depth. It was easy to install with two people to ensure it stays level.