*The 5 position switch not only allows you to combine pick-ups but also allows phase switching of the coils....I'm sure other members here can give the exact specifics, but understand that pick-ups are a coil of wire that induces current around a polarized metal....by phase-shifting, you can change the dynamics of the induced current, there-by changing the "signal" (field of induction) that goes to your amp.....Sorry if I'm vague....I know others can explain it better....