This is a support bracket to hold the back panel of my Ikea LACK Table Enclosure on.
I ran a couple prints and they turned out great. The M5 hex nut fits snugly in the piece and will not fall out!
The screw hole is for a #8 screw
The Hex nut fits a M5 - .8mm
The screw spot allows me to mount it to the table while the hex nut allows me to screw the back panel in, to hold it in place.