The digital controller technology with solid state relays create a top quality 5 step transformer. Made in Europe to the highest quality standards, the silent seamless changes between steps removes the loud clicking that some controllers have. 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 your grow room close to your set temperature all the time. Heater control – max 2.5kW. Up to 13 amps. Maintains your grow room temperature. Fan motor protection.