This is one of the most wonderful, interesting, strange things I've ever seen. It's a synthesizer that's only purpose is to imitate train sounds. At first I couldn't understand what this could possibly be for, and I'm still not certain but I suppose it must be for the serious (very serious) model train collector - which, will probably be me and Peter someday.
Turns out Matrix Synth did a post on this years ago. So, rather than repost their pictures I'll just direct you to said post:
It is so interesting because mixed in with the more common synthesizer parameters such as cutoff, tone, echo and reverb you also have throttle, exhaust, wheel noise and bell.
There's also a module that plays three cassette tapes on a loop called the "Quadratape 3 Player"