The "Fleck" part of the system is the control valve (the "brain" on top). While the tanks may vary by brand, these are the three most common Fleck valves you’ll encounter:
Choosing a Fleck valve and softener system : r/WaterTreatment buy fleck water softener
Justifying the price of Clack WS1 systems over Fleck 5600/2510 The "Fleck" part of the system is the
been down this rabbit hole myself. the main things to look at are grain capacity (based on your household size and water hardness) Reddit·r/homeimprovementideas manufactured by Pentair
Buying a Fleck water softener is a smart choice for DIYers and homeowners looking for a "workhorse" system with readily available parts. Fleck systems, manufactured by Pentair, are among the most popular and reliable control valves in the US.