A mount designed to fit 100mm VESA bolt pattern often found on computer monitors.
The centre hole is 6.5mm(1/4") and the counterbore is 12mm in diameter. This should accommodate 6mm and 1/4" bolts.
The photo shows it attaching the monitor to a wooden arm. I used a 1/4" diameter wood screw to join the two.
I printed this in PETG with 2 perimeters and 15% infill, and it seems strong enough.