Alternatively, rubber pads have relatively higher natural frequencies and damping capacity at higher frequencies with respect to steel type isolators. On the other hand, operating temperatures for rubber pads are limited considering the material characteristics. In addition to limited operating temperatures for the rubber pads, low creep resistance and age stiffening can reduce the isolation capacity during time. As another alternative, a special type of isolator element, namely pneumatic springs work with a control unit that adjusts the leveling and the stiffness characteristics of the isolator element automatically. Low frequency vibrations can be successfully isolated by those springs, however it requires significant amount of maintenance during operation life. The design limitations for the current design are given as follows: