https://www.amazon.com/Kuryakyn-3990.../dp/B00E1ZRQL6

Vs

https://wingstuff.com/products/35211...fit-f6b-gl1800

View the images.
No arms on II means further forward than III.
Arms on III are telescopic so the forward position is further back than on II.

It depends on what you're after. If you want fully extended legs then you probably want II.