What is the difference between a dSF11, dSF12 and dSF20? digitalSTROM Support September 28, 2018 06:02 Updated Follow The filter has been constantly optimized (better filter performance, function display etc.). The dSF20 should be used for new installations. Related articles How many filters dSF need to be installed? What does the colour of the LED of the dSS mean? Can I control digitalSTROM by voice commands? Where are the dSF filters to be installed? How much power is required to protect a dSF filter?