Snap-on 1/4" drive deep well or extension ?

[garilla]

Found this gem in a bunch of stuff from an estate sale, is it an extension or a deep well LOL. He used Snap-on M 10 G code (WWII?) 5/16" for the base and M 6 3/16" (1942) for the small socket brazed together with a piece of tubing in between. I wonder if I'll ever need it, honestly I can't say I've turned many 3/16"

 

[Stubby1743]

Neatly done, but you've got to ask why?

 

[Oldtuleguy]

3/16 nutdriver/deep socket