This is very likely an "H"-type sync cable, which looks like an ordinary household electrical cord, but DON'T PLUG IT INTO AN ELECTRICAL SOCKET. Shutters that had bipost sync terminals could be connected to a strobe that had an H-type sync socket using an ordinary electric shaver cord. Paramount, as Mike mentions, makes other kinds of connectors, so you can connect a camera or shutter with a PC contact to a strobe with H-type sync. This is only a sync cord; it doesn't power the flash.

Older and some current strobe pack systems like Norman (also Norman portable strobes) use this kind of sync connector, but it's become less popular, due to the obvious safety concern that someone could make the mistake of plugging a camera or shutter into the wall, but an advantage of this system is that it works with ordinary electrical extension cords and power strips.

There are also slave triggers that plug into H-type sockets.