What are these things?

[priceman1414]

I have this rotating bit / nut driver holder, and my dad has one just like it. There are these two grey tubes with coil springs in them. In the holder, they are labeled 'S/F'.

Any thoughts?

 

[pstemari]

I think they're for holding the head of a screw while driving it. Will they fit over a screwdriver bit?

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[ssdave]

Those look like 1/4" hex screwdriver bit holders to me. They are used to set a screw flush with the surface, you insert the screw into the holder, engage on the bit inside, and it allows the driver bit to cam out when the screw is flush with the surface. Good for use with flat blade screws and a power driver, they keep it centered so it works. But, they scratch the surface when they cam out and slip.

 

[stg454]

That's correct. They're screw holders. Haven't seen them in a while.