Hydraulic or pneumatic pistons are used in many mechanical applications where linear motion and force are required, and the most important part is the sealing elements. In applications where sealing elements such as seal, dust seals are used, they have a pre-tension in their ducts after assembly. In the non-pressurized sealing element, it is necessary to create a pre-tension in the channel and a gap in the channel that will enable it to work comfortably. Thanks to the pre-tension, the sealing element fulfills its duty at very low pressures. We see that the sealing element under pressure works by spreading thanks to the pressurized fluid filling the channel space. Sealing elements are produced from materials that change their form when force is applied on them and can return to their original shape when this force is removed. This is why sealing elements are produced from elastomers or thermoplastic elastomers.