Driver side input powers relay 1 and that relay sends power only to the Driver side.
Passenger side input powers relay 2 and that relay sends power to only the Passenger side.
The best part about this harness is if your vehicle requires resistors or capacitors (both sold separately), you can easily connect them directly to the input of this harness.
This harness can be used with most HID bulb sizes, not just 9005 or 9006, but if the HID bulbs have a power wire that utilizes the 9006 female connectors with yellow waterproof grommets. This will work with all of the Xenonsplus, Morimoto, GP Thunder Pro bulbs: H1 (not Morimoto), H3, H7, H8, H9, H10, H11, 9005, 9006, 9012, 9145, D2H.