I wondered too! So I went to their site & found this explanation:
The S.F.S. system allows the pistol to be carried with the chamber loaded and the hammer down. When the pistol is carried in this condition, the hammer is locked, the sear is locked, the slide cannot be opened, and the trigger is locked.
With the three safeties activated the S.F.S. allows the hammer to be cocked, and the safeties are then deactivated by simply pressing the ambidextrous safety lever with the thumb. The trigger pull remains light and accurate, allowing a very fast first shot.
Is that "whirring sound" Jeff Cooper spinning over in his grave??
Here's the link:
http://www.cylinder-slide.com/sfs.shtml