Fox front Air Shox apart for servicing The assembly Valve stack, their is the same thing on the bottom side you just cant see it because of the spring. Here it is taken apart everything is laying in order Notice the broken top out spring :-( I figure it was stressed when I had the rebound setup wrong and could feel the shock knocking when the front tires left the ground. The valve stacks You can see the broke top out spring, what the spring does is every time you extend the shock it will act as a cushion when the shock is fully extended, with me driving my Pilot with the wrong rebound dampening every time the tires left the ground they would make the spring compress to the point where they would bind, I changed the rebound valve stack for more rebound and went to a 15 weight oil. The shaft acts like a piston, and the shock compresses the piston or shaft displaces oil the more it displaces the less the area in the shock and it compresses the nitrogen this resistance acts as a spring just like you see on the outside of coil over shocks, the oil level in the shock body will set the compression ratio or spring rate of the shock. The inside of the shox body, see nothing in their just the cap that is welded on the other end sporting the valve stem used to add the nitrogen, the wall of the shock tubing has been honed to a fine finish for the Teflon ring to ride on.