This is a remix of Atziano's excellent cable holder, but with bigger holes.
This part is for attaching the wiring harness that leads from the hotend to the control.
The cables are led straight up to avoid a collision with the delta arms.
Moreover, this also means a strain relief for the cables from the hotend.
I found my socket cap screws would not easily fit, possibly due to my printing. This model takes the original, and enlarges the screw head space to 6mm.
The second picture shows the original dimensions on the left, and this remix on the right.