Humminbird Transducer Switch

I recently acquired a transducer switch which will allow me to select front or back transducers from my 788.
The switch has two power leads in addition to the normal transducer leads and the switch to head leads. My question is: what is the function of the power leads to the switch.... doesn't the operating transducer get its power from the head? If this is the case, need these leads be connected or can they just be isolated. Instructions coming with the unit only say to hook them to the fuse block.

Those power leads are for the relay the does the actual switching from one transducer to the other. The “switch” that you toggle just energizes or de-energizes this relay. For the relay to work, those power wires have to be connected.

Thanks, Greg! That clears things up for me...... mounting instructions didn't elaborate what their function was.