Pro Mag 12/20 Amp Electronic Points Box The Points Box Controls The Spark Duration And The Unique Full Power Firing Of The Pro-Mag 12 And 20 MSD IgnitionThe energy from the generator is controlled with Field Effect Transistor (FET) technology, which is far superior to mags still using points as a trigger source. FETs are much more accurate, durable and capable of handling much more current This is why the Pro Mag is capable of delivering full energy sparks throughout the entire rpm range of the engine, while conventional magnetos fall short of full power at high rpm. Plus, the Electronic Points Box