The model is for passive cooling of a VESC 75/300 Trampa, you are all free to upgrade the mast clamp. Attached is the DXF of the mast that @nice2cu drew for me and that he allows me to share with you 
https://onedrive.live.com/?cid=f57695981b714e05&id=F57695981B714E05%2134935&authkey=!AN8iKoHGzQ5HvJU
Thanks Robert.