# What is the purpose of an inductor on an incoming AC line?

I am trying to build the following schematic. It is a AC/DC converter from Cui link

1. I do not understand the function of L2. What is its purpose?
2. I am having a very hard time finding L2 for sale. Most inductors with a value of 5 mH are out of stock, and the selection is very poor. Could someone recommend a more common value that would still work in this schematic?