Plug & Play Dual H4 Adapter Harness: The H-4 Dual harness is needed if your bike has an H4 connector on the headlight. This harness will work with both single and dual headlight motorcycles and with most Harley Davidson Motorcycles or motorcycles that use a Dual Filament Bulb.
Plug & Play H7 Japanese Adapter Harness: This is the harness you need if your bike has an H7 Japanese connector on the headlight. This harness will work with both single and dual headlight bikes when connected to the Plug and Play Headlight Module.
Plug & Play Single H4 Adapter Harness: The H4 Single headlight adapter harness will ONLY work with a single headlight motorcycle.
Plug & Play Universal Adapter Harness: The Universal harness is meant for motorcycles that are incompatible with the other harnesses listed here. Mostly when a motorcycle has mixed or two different connectors. This harness does require cutting and splicing of your factory harness (similar to the original Diamond Star Headlight Module).
NOTE: In order to use harnesses listed here, you must also purchase a Signal Dynamics Plug and Play Headlight Module™