At the six-month mark, Tate began trying to pull up on things, and we knew it was time to install the Montessori bar on our mirror. The bar is installed at chest-height for the baby, which I think is approximately 17 inches. The baby uses it to pull up into a standing position and later practice cruising.
We had a neighborhood handyman install it the first time, but it pulled right out of the wall! The next time we asked our friend to do it. At our little New Year's Reflection and Resolution-setting party, my friend and I decided that her husband would install our white board and railing for Tate, if we taught her how to cook a soup and had her and her family over for dinner.
He decided to install it into the wood frame of the mirror because the spacing of the studs was a little off. Installing it onto the frame of the mirror meant that he had to saw a little of the bar off, which seemed to be pretty simple for him.
The bar is simply a curtain rod from IKEA. You could also think about using some hand railing material from a home improvement store like Home Depot or Lowe's.