there arent any.
that was my point.
a few yrs ago there was a bachur who began wearing one
it was a big problem
most people here wont understand this, but this little bobby pin was a sign of discontent and rebellion
it threatened to poison the Holy atmosphere
it was dealt with
first kindly and gently, then more firmly
i dont know the eventual outcome
see both of my posts
in my first one i said Telshe was makpid on not wearing bps.