The RS400 wing wangs (the lines that control the sideways movement of the pole on the RS400) have a 6mm plastic stopper on them then  a bowline with a piece of tubing round it. This is then pulled from forward (in front of the mast step) with the pole across to the side and tied tightly. This allows the bobble to hit the bowline knot and stand the handle in the air when the pole is set for the opposite side.

If you need an RS400 wing wang line that will last - Rooster Halitec is the answer.  Steve Cockerill has had this rope on his own RS400 for over a year now, and its still looking in great shape. With a 16 plait Technora/Polyester twist mix outer for superior wear resistance and cleating, and an inner core of 12 braided pre-stretched SK78. This combination means it will not stretch.  Half the supplied length of halitec and you have more than ample to ensure your passive handle does not restrict the projection of your pole. The length of this rope is enough to replace the wing wang lines, including a plastic tube handle (not supplied - see the related items) on each line and a little slack even when fully across. 

For more details on gybing the RS400 and the wing wangs please see Steves Blog post HERE