if your referring to the main arm clamp then its not a set position so to speak you adjust the clamp to suit the travel of your dish from east to west, So only you can decide its final position
I wound mine out by about a inch, fixed it to the unit and adjusted it so the dish went a few degrees west past 0.8, and set the limit on the unit and receiver.
So it all depends on what satellites you want, or can cover. 24" will cover a very big arc.