The CF3 uses two carbon leaf springs. Once you adjust the saddle tilt on the seatpost, which admittedly is much more difficult than a normal seatpost, there is a bolt at the bottom at the two leaf springs that holds them together so they don't slide. Additionally the force of the seatclamp holds the two leaf springs together so they don't slide. So they do not slide while in use. The two leaf springs bend to provide suspension. As I already stated, setup on this post is a little tricky, but its well worth it. One of the problems is that if you don't get the bottom bolt or seatpost torqued properly then you can get slipping of the post and/or leaf springs, so a torque wrench is really required. You also need to use carbon assembly paste, but it comes with that.
Okay, that makes more sense, I figured thats what that bolt was for, but wasn't 100% positive.