Transitional Systems Doubler 2 Valves on One Wire. Doubler is the quickest, easiest and most cost-effective way to add new valves or repair damaged valve wiring. Doubler simply connects new valves to an existing valve while allowing you to control all the valves as if each were hard wired to the controller. Doubler eliminates the need to run new
wires saving you the time, expense and hassle of digging and trenching.