Not sure what it's called but I do know the guys up at the Cape Horn factory know. One of the main guys who was working at the front desk was telling me about it when I did a tour back in the summer. He said that it makes a big difference. If you figure it out let me know depending on price I may be interested.
I did some searching and found this website. I think it's what you're talking about buta little pricey.
http://www.fastrails.com/
Here is their number for Cape Horn <SPAN style="FONT-SIZE: 11pt; COLOR: #7f7f9d; LINE-HEIGHT: 113%; FONT-FAMILY: 'Trebuchet MS'; language: EN">(850) 626-2211