This ensures the luff cringle doesn't unhitch itself from the hook or line you have just put it on.
I never really did solve the problem of keeping the foresail luff tight on a Jack Holt roller spar - anyone else cracked it?
The kite does n't luff, proven to be ideal for beginners and advanced riders!
A useful side effect is that they can be used to increase the tension in a jib luff.