Controllers are used to regulate the pump power allowing variable flow. In most instances this is either 12 volt or pneumatic. 12 volt controllers are generally specific to the pump used whereas pneumatic controllers are generally universal. Pneumatic controllers vary the time between pressurization(discharge) and depressurization(refill) allowing flow rates to be controlled by timing of each cycle. Most pneumatic controllers no matter branding can be used with variable brands of pump. Typically a universal pneumatic logic applies.