I can't be positive but it's probably between 12-15 to 1, I think the beauty of this internal cascade system is the extra purchase for less residual sheet and also the cost.
How it actually works has been explained to me but unfortunately I was at the bar at the time so now I haven't a clue <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />