The machine itself is a base 9900 Zig-Zag from 1912 then in the 1930's Galkin got it and converted it into their "Waist Band Machine" See the cast covers with that on the gears! Also a Galkin Belt cover on the back! This machine is a zig-zag chain stitch with a built in Roller to handle heavy material and keep it from drifting. I've never seen another machine like this.
It could be the only one. Sews a clean chain too. I'm cleaning out some Antique machines I don't use and I'm trying to make some space. The item "Antique Union Special Galkin Waistband Zig-Zag Industrial Sewing Machine" is in sale since Thursday, June 22, 2017. This item is in the category "Business & Industrial\Manufacturing & Metalworking\Textile & Apparel Equipment\Sewing Machines".
The seller is "happyhooligan70" and is located in Burbank, California. This item can be shipped to United States.