That is a nice Improved Family. Model 12 is not a high arm machine, so it's easy to tell them apart.
I have two, and they both take a different bobbin than the class 15, it's just a bit narrower.
this is one of mine, slightly later version
and an earlier model that has a different way to adjust the foot presser, and the bobbin winder was on the belt guard instead of the machine. I'd like to see a picture of how your bobbin winder is mounted as yours is the first I've seen like this with a bobbin winder not on the belt guard. I'd love to get a bobbin winder for mine that mounts to the machine.
it's also neat to see that your belt rides on the outside of the flywheel and not the inside, so it may be an industrial version. Singer made a lot of variations of this machine for industrial use.