OMG! I had found exactly the same adapters only a few weeks ago. Was looking to make a T-handle with three bit holders AND a spinning ring. There are models like that out there but none that have all my requirements. So I thought of getting a 5mm (or 6mm) T-handle with a spinning ring and add 3x...
That description is terrible. It has a true 1/4" hex female hole as verified when putting a 1/4" DR - 1/4" HEX bits into that end (in addition to fitting the 1/4" shaft of my Duron). Not sure why they used metric in that case; it should say 6.35mm anyway.
Love how deep that adapter is.
I made a 1/4" FEMALE HEX to 1/4" FEMALE HEX adapter that fits on the big slotted blade (over the tip) of my DURON Retract-A-Bit screwdriver, thanks to its shaft being a 1/4" hex. I can now use my multi-blade DURON as a bit holder.
The adapter is a hack made of two others expoxied together...
Wondering what those adapters were used for. Once put on a ratchet or handle, were they used to turn some kind of 1/4" square nuts / taps on refrigeration units?
Hold on @KnurledNut : why not simply using a 1/4 Inch Drive x 1/4 Inch Hex Bit Socket as a M Hex to F Square adapter? Of course it won't provide retention but that would work in a pinch.
https://www.amazon.com.au/TEKTON-Drive-Hex-Socket-SHB02206/dp/B07RBMWHFK
Further to what @RPH mentioned above:
https://www.amazon.com/CDI-Torque-342-40-Socket-Adapter/dp/B0155A53S8?tag=atomicindus08-20
https://shop.snapon.com/product/Female-To-Female-Socket-Adaptors/Female-1-4"-Square-x-1/4"-Square-Socket-Adaptor/342-40
seem to be the same thing.
EDIT: that is...
Similar to the GEARWRENCH 890007GD coupler is the BAHCO R6967. Much shorter at 1.76cm, compared to 7.62 cm for the Gearwrench.
I ordered the Bahco from https://www.redboxtools.com/ . Seems to still be available at...