'Wings' have, I believe, a rear preload that is electrically adjusted. Kinda like this:
http://www.google.com/imgres?start=2....4000244140625
The F6B has a 'similar' system, except the adjuster is a manual 'rotary dial' type hidden behind the (RH?) side cover. A 'remote' preload adjuster similar to this:
http://www.cruisercustomizing.com/images/PS-465_200.jpg
I believe there are 38 'clicks' of adjustment. Most are set at "0" from the factory. (Least amount of preload)
IMHO, the rear suspension on mine is a tad stiff,,, Could be because the last bike I had was pretty 'plush' if not a bit too soft. (Yami Stratoliner)