It's a bracket for KCEVE KC-KVM401A KVM switch for mounting it on VESA plate.
On photos it's combined with https://www.thingiverse.com/thing:1935823 pole bracket but also can be used with any VESA 75-100 plate.

STL should be printed two times, one stright and one mirrored. Besides that you'll also need

• 4 or 6 M5x10 or M5x12 countersunk screws to mount it on pole bracket as I did.
  or
• 4 M4x12 countersunk screws with 4 nuts and 4 washers to mount it on standard VESA plate

Mounting holes prints better with supports but it's not really a requirement.