It adds support for your load, keeping your otherwise droopy bags away from the indicators/exhaust etc. The ribbed sections of the Support fit directly over the bars of the SIP carrier and it’s secured using the re-useable extra strong tie wraps provided. This allows the Support to be removed when not in use, or when you reach a rally.
Always be sure to bungee or attach your luggage directly to the rack as well as the Support.
See one being fitted here: SLUK Support