Only high quality over specified components are used in the construction to deal with the stresses of switching high currents and voltages and keep temperatures low giving long life and durability. 
Magnetic Pulser - Internals 1
Magnetic Pulser - Internals 2
Magnetic Pulser - Internals 3
Magnetic Pulser - Internals 4
Life Pulser 600V internals showing parts.
This video link to Youtube shows what is inside the unit, take a look: