Review on 🔩 Tripp Lite SRCAGENUTS Cabinet Square Hole Hardware Kit - Rack Enclosure Screws, Washers by Aaron Lewis

These are honestly the easiest to use cage nuts I've tried. You can easily insert them manually. The M6 size is great - it's stronger and easier to start / harder to screw in cross threads. The only thing to note is that the M6 will not fit in the holes of some rails and devices. If you have a big install planned, check that out first and when in doubt, order some M5s for the crazy ones.