For less than $10, you can find a file rod that will fit, not bend under the weight of lots of files, and is so simple to install that anyone can do it. Don’t go to Staples or another office supply store to buy a flimsy wire cage when you can get something that the desk should have came with anyway. It can be tough to find the right thing, even when it is something small and seemingly insignificant. I’ve looked for years to find something to recommend to people trying to load up a file drawer on a desk- and here it is.
Check out Wood Worker’s Supply