What exactly do C+C plates do?

[MAC'n89Blckstng]

My friend is in the process of ripping apart his car and he took off the shock tower nuts and showed me that there is a lot of camber adjustment with the stock plates? What does aftermarket plates do?
Thanks,
Jesse

 

[ECU5.0]

there is a lot of caster camber adjustment in the stock ones...but once you lower the car you can adjust them enough and as accurately as you can with aftermarket ones.