This is a rack ear meant for a Cisco SG300 series switch, specifically the SG350XG. The bolt pattern is 20-28mm squared (20,24,28 steps) so it's a bit more universal. I'll be posting a very similar one as a universal rack ear that's not as long as this Cisco one.
You can use either countersunk or non-countersunk (Pan head) M4 machine screws with this design. The mounting holes for a server rack are meant for M6 machine screws but you can go a bit larger or smaller.
Print Settings:
Note: This should be almost solid, bump up the wall thickness before the infill so it's stronger.
Material: PETG (VoxelPLA Pro eventually failed after 3 years)
Walls: 3mm+
Top/Bottom: 2mm+
Infill: 40%+ (Make your walls + Top/Bottom thicker first)
Update 9-19-25:
After 3 years the ones I printed with Grey VoxelPLA Pro failed for my heavier Cisco 10G switch. Upon inspection, I should have made the walls nearly solid and used PETG from the start. Use PETG and make the walls nearly solid. I always leave a little bit of space in case it overextrudes a little bit it can go inside the model and not force out through the top layer or walls.
The author marked this model as their own original creation.