Carbon Fiber
From Spydiewiki
CF is an acronym for Carbon Fiber. Graphite fibers (the size of a human hair) are woven together and fused in epoxy resin. It's lightweight, three-dimensional in appearance and is a superior (and expensive) handle material.
Spyderco uses CF on its higher priced models.
See the "Spyderco Carbon Fiber" thread by "The Deacon" for an overview of the different types of carbon fiber used by Spyderco.
