Vaporman87 wrote :I guess they were used to power radios and such before homes were commonly wired for electricity.
Okay... what's a socket power battery eliminator? -end quote
http://home.earthlink.net/~chestnutl/Batteryeliminatorspage1.html
This unit was an accessory that allowed you to use AC power, rather than batteries to power your radio
No more having to lug the batterys down to the local garage to get charged there or pay for replacement "B" batteries.
It gave power from a socket, and eliminated the need for batteries... although it was really just a big battery in a case.