Here is the infamous Marx whistle which was produced to compete with Lionel's whistle tender. Having had both in my train collecting I can tell you that this one is more reliable, sounds better, is easier to operate and easier to maintain. None of that engineering overkill employed by the little lion!
This one is still in it's original package!

(Courtesy of David Allen)



As usual another version of the Marx whistle has surfaced. As can be seen above the lithographed whistle is made from the same tooling (or was extremely well copied) as the Marx whistle. While the litho does not wear the Marx logo the train depicted looks something like a British Marx Coronation.

(Courtesy of Paul Wasserman)