My Honeywell Heiland model 65A 'potato masher' flash has two connectors.
There is the one, that takes a plug that looks like a household plug, and has a PC connector on the other end. This goes to the camera PC socket, and is what triggers the flash. See the cord at the left in the picture below.
The other connector is an oval recess with two pins. This takes a power cord that provides house current to the flash so it can be operated on 115/120 VAC, instead of the three 'C' cells.