The mail bag set was made for both O gauge and Wide Gauge, with size differences in the stand that holds the mail bags. A typical mail bag set includes a stand that attaches to the track and holds a mail bag, a clip that attaches to the baggage car at one of the door openings, 4 mail bags, and a hook to fish the mail bags out of the car, once they have been picked up.
The basic principal is that as the car goes by the stand, the clip on the car picks the mail bag and flings it inside of the car.
One problem with the mail bag sets, is that the clips that go on the side of the baggage car tend to scratch the side of the car.
I will try and get a picture posted later.
