These mid-1900s "adding machines" are a work-alike for Pascal's La Pascaline, built in 1645.
They were used in my classes teaching the methods of early calculating devices and do an excellent job of duplicating the adding and subtracting done by Pascaline.
There are only 10 of this size and there is some variation in color.
Each device is $20 plus $3 s/h.
They are in working order.
I have other models available, some in brass. See my TPT store.