By exploding the left photo you can just see some ‘shiny’ shims above the port hole of the piston. These are forced back by the oil as it rushes through from right to left as you view it. The distance the shims move here is called ‘the float’. They stop moving when they hit the rim on the large nut. The small drill hole is your rebound bleed, you control this from the top of the fork leg. Below the piston, towards the nut on the right, is the rebound shim stack (unseen here).