The Pulley Stopper at the bridle of my OR Flite Kite wasn't stopping the line anymore from going through the pulley as it was worn out. Result was a strong pull to one side of the kite.
This model at least works for me.

Please use only if you know what you are doing, as it might be a safety relevant part of your kite. Consider getting a spare part from the supplier (which I did not find for my location...).

Print in TPU with small layers, no support needed.
Do not print in PLA / PETG (temperature & potential mechanical abrasion of lines)