These jumpers are used to configure the ECU for special applications or uses to enable optional features. If we've not specifically suggested you purchase one of these in order to do a specific function the ECU was not designed for, then you don't need one. These are used in special cases only. The jumper wire uses a crimped and heat shrunk connector on each end to slide over the jumper pins in two different locations on the board in order to move a specific function to a different pin number.