Here's a view of the business end of a monster-sized 4.0 King Kong shock. On the top of the piston, you can see the intake ports for the compression stroke around the perimeter. The rebound shim stack is bolted to the top of the piston, and the progressive diameters are easy to see. Brett King informed us that "Shocks are like engines. They need to run at around 200 degrees to work properly. At that temperature, you can't touch the shock or it will burn you, but that doesn't mean it's overheated. At the same time, 300-degree shock oil is too hot. At that temperature the oil will break down."