This is a simple platform to mount a rubber cable organizer, specifically the one or two cable circular mounts like those below.
https://www.amazon.com/dp/B07PTZ7LLR?ref=ppx_yo2ov_dt_b_product_details&th=1
It uses an M8x16 counter sunk bolt and M8 t-nut.
The author hasn't provided the model origin yet.