WCI pocket screwdriver with triangle socket...

[turbokinetic]

Hi folks.  A friend has this group of screwdrivers, branded WCI, Frigidaire, and other brands which were part of WCI. Some have a magnetic tip in the handle.  On others, the butt end of the handle has a triangle recess in it.  It's too small to be where a magnet fell out. 

I have a feeling I have seen some sort of adjustment screw on something (thermostat maybe?) which had a head on it looking like it would fit that socket. Can anyone identify what this was used for?

 

Thanks!

Sincerely,

David