Funny this topic came up, I had seen one of these a long time ago, but like a dummy passed on it for $5, at the time thinking it was a gimmicky, Sears fathers day special type tool. Forgot about it, then recently spotted one on ebay.
Channellock no. 906 "universal" drill chuck-style socket, 3/8 drive, made in USA. I found an older post in the GJ archive where it is mentioned these were made by Milbar for Channellock.
Milbar is well known for their safety wire twisting pliers, but nowadays it looks like they are owned by Imperial, and it appears this socket has been discontinued for 20+ years. Most used examples look new, if that says anything...
Edit: rated for 1,200 in/lbs of torque!
Capacity: 5/16"-5/8", 8mm-16mm! Replaces 20 sockets!