That's where our 4026 "Y" Connector Cable comes in handy for that fourth flash head. Just plug the one male side of the 4026 into the power pack (with the power off, of course) and connect two flash heads to the 4026's two female connection points. Keep in mind that the fourth flash head borrows power from the other three heads. So, the power output of the pack is redistributed, when the 4026 are introduced. (If you have the older Novatron 5 pin connector on you power pack, you'll need our 4012 Adapter to us the 4026.)