This is a mechanical unit used by railroads for sending a pre-determined signal. The knob is turned winding a spring. As it returns it uses a cam and switch contacts to send a coded signal. It is housed in its original wood box. Asking $125 plus shipping.

Shipping will be at actual cost with tracking and $50 insurance included. I will combine shipping on multiple purchases where practical. I accept money orders, checks, or PayPal – Friends & Family.