This is a picture of Custom Flight Creations flap differential adjustment mechanism. Should there be any difference between the flaps when fully retracted this screw mechanism can be used to set both flaps identically. Also, should there be some roll present in the aircraft when trimmed for straight and level, this screw can be used to droop one flap the tiniest amount to correct that roll. Bud says you adjust the screw (which goes through the baggage bay wall and against the flap cross tube) in 1/8th turn increments at most.
