Two (2) vintage unusual machinist's jacks

Two (2) vintage unusual machinist's jacks

I have been looking on e-bay for several weeks and have not found any that are like these.
The minimum working height is about 3 1/4 ", and the maximum working height is about 4 ½". The working height is adjustable with two (2) screws, with the top screw being a smaller size. There is a locking nut on each screw.
These jacks have been around for a long time and there is still a lot of work left in them. There are a few nicks and a little wear here and there but nothing that would keep them from being used. I am sure they were of the best quality when new.
I do not see any name of manufacturer.
The item being offered is from the estate of a machinist who retired 40 years ago. I am selling these items for a friend.