The hydraulic cylinders operate with the principals of fluid mechanics.  During your exercise the fluid is forced from one chamber to another.  Resistance is determined by the speed and the adjustment of the orifice from one chamber to the other. This is a key feature of the home gym and it allows the resistance to adapt to your strength level.

The cylinders have a graduated resistance dial numbered 1 to 12.  Each cylinder has an arrow to indicate which resistance is being used.  The arrows on the front and rear leg cylinders face the ground.  The arrows on the top and bottom vertical cylinders face away from the machine.  The arrows on the chest fly cylinders face inward.  Start your exercise at the lowest resistance levels and gradually increase the resistance as you gain strength and endurance.  The dials are intended for a reference to chart your progress.  Both the dial setting and the speed of the exercise determine the resisting force.  Need more resistance? Challenge yourself by increasing the repetitions of each circuit exercise as you progress.