There are no instructions, so I guessed the size of the drill hole for the plastic inserts, but guessed wrong and shelf was wobbly.
Uninstalled the shelf, fixed the holes and tried again, this time I guessed correctly.
It was difficult getting both sides level since the walls were not exactly 90 degrees. A template strip to mark hole location would have been useful. After I finished, I realized that I should have made one myself.
Nice shelf but hard to install
There are no instructions, so I guessed the size of the drill hole for the plastic inserts, but guessed wrong and shelf was wobbly. Uninstalled the shelf, fixed the holes and tried again, this time I guessed correctly. It was difficult getting both sides level since the walls were not exactly 90 degrees. A template strip to mark hole location would have been useful. After I finished, I realized that I should have made one myself.