What is this socket used for?

[snapmom]

Model number IP-19S no date code, looks like 40s. Has sort of a torx like opening. 1/2 drive. Reads Snap/on, 9/16-P-180, IP-19S, 785564

[wreckercologist]

Do you think it might be surface drive, like used on assembly lines?

Here's a link to a page in the 1979 catalog.

http://www.collectingsnapon.com/catalog ... gPage=3583

Similar part number..............might not mean anything. I know in the later catalogs, they offered "surface drive", but I believe it was more of a six point like you have.

[wreckercologist]

Page# 103 in the #400 catalog shows a pretty good picture or surface drive, which appears quite similar to what you have.

[snapmom]

That fits, its a 9/16 surface industrial power socket.

[ToolMike]

What you see is a socket retention design that was more positive than the detent ball.
It required the use of complimentary socket design.