Global Air Supplies Pro Plus Step Controller (UK Plug) is a quiet, simple to use and the most efficient way to regulate the AC fans, with no clicking between steps. The digital controller technology with solid state relays create a top quality 5 step transformer. Made in Europe to the highest quality standards. The Pro Plus Controller has the same top quality transformer and silent step transitions as the pro version. It has the addition of a heater control that works in unison with the fan controller. Keeps the grow room close to your set temperature all the time.