Help IDing these sockets - 3/8" dr. US set of something

[Etown88]

These are perplexing to me and others iv3 asked, they qlmost remind me of the changeable torx sockets but dont have an allen screw to tighten or a retaining ring - seems like a 1/4" sq. down inside but 8 diff sizes? They only have "WARNING WEAR EYE PROTECTION FOOL" & USA #1-#8... IM sure it wAs part of a set, found it in a drawer that was my uncles, always ignored it since you cant see the words (USA in particular) while its in the holder...
Does anyone know, (EDUCATED Guesses may suffice)
Thanks for your time either way, i have no clue of brand or function or (not that it matters...) worth!

 

[dopod]

Tap sockets

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[PelicanPines]

Yep, tap sockets... I have the same set, in the same holder... Very useful.

 

[RedneckWelder]

Lisle tap sockets. They also rebrand them for the tool trucks and they make a larger size 3 pc set. I use the hell out of mine they are awesome.

 

[Etown88]

Ah gotcha, thanks everyone -