ThyssenKrupp Bilstein Suspension supplies air suspension and damping modules. Air springs make it possible to vary the air pressure in the boots and set different vehicle heights. In addition to compensating levels in accordance with different degrees of loading, they also permit different aerodynamic or off-road positions. Increased spring rigidity due to higher pressure results in an intrinsic / built-up frequency that is more or less independent of load with simultaneously declining damping ratio. This negative effect can be compensated by using an adjustable vibration damper.