Don't tear up your fingers trying to install or uninstall pesky cage nuts. Use a Cage Nut Tool from RackSolutions instead! This stainless steel tool comes with a hard plastic covering that includes a quick and easy, "U" space size reference guide on the back.
It also features 3 holes (10-32, 12-24 and M6) that are sized and labeled for you to easily check to see what screws you have. Below is the installation of a cage nut into a square hole rack.