GSE Step Controller Overview GSE Step Controllers allow accurate control of fans at low speed, without any low noise hum, which is often associated with fans running at low speeds. The unit controls the fan speed based on the temperature of the grow room. The low voltage sensor is on a 4 metre long cable and the temperature and sensitivity are controlled independently. The controller has a water-resistant cover and comes with a peace of mind 2 year warranty*. The step controller comes in 2 power options either 2.5 amp or 8 amp depending on the specification of the fan being used. All G.S.E products are engineered and manufactured in Europe and are available exclusively from Growth Technology retailers.