steinheil lenses

[RumpFace]

I've just given one of these a new home to live on my OM10.
I saw it on ebay and nabbed it for less than a night in the pub. But I know next to nothing about these about lenses apart from they made some very nice units. There's only one way to find out I know but does anyone know much about them? Mines a 28mm F2.8.
Serial no starts with a 75 so is that the year it was built?

 

[RumpFace]

That should read lenses.

MOD EDIT:IT DOES NOW

 

[StephenM]

Have you looked here?

 

[RumpFace]

Yes, thanks. Frustratingly mine isn't on that page. I don't think mine is as cool as those but it seems nicely built.

 

[StephenM]

Any description, or any other designation engraved on the lens?

 

[RumpFace]

This. ☺