there seems to be 2 common lengths 90cm and 100cm or thereabouts.
The Kite foils have come from a racing background and the extra length allows more lean angle for racing upwind.
I freeride the shorter mast looks the goods.
but in learning the first steps are a slow climb till wings breaks surface then crash down so a longer mast gives you more time to react.
the shorter mast is lond enough and lets you start a bit shallower.
there is a lot of info on this link that is good.
kiteforum.com/viewtopic.php?f=196&t=2391074primarily about windfoiling. and lots of good vids.