A "switched outlet". [Linked Image]
[Linked Image from usfamily.net]
This is made by Arrow, part #8668X. Stamped on the face of the receptacle and on the yoke, one can read "10 A. 250 V." The snap switch mechanism is two pole, single throw with a pair of brass terminal screw for the line at the top (as shown in the photo). As set of brass load terminal screws are on the bottom. I found the device connected to a 120 volt hot and neutral, but the load terminal screws weren't used for anything down stream.

Al

Al Hildenbrand