Perfect for anyone wanting their Holley EFI ECU to control more functions or monitor more data channels HP and Terminator X EFI installations with only (4) inputs and (4) outputs can now add more functionality to their EFI system Expand Dominator ECU’s Input / Output control with (8) additional inputs and outputs Inputs can be used for things such as: -Switch 12V Toggle Switches - can be configured for external mechanical relays or setup as digital switches via a Holley EFI dash