O-rings are rubber sealing rings with a circular cross-section. Because their cross-section is O-shaped, they are called O-form sealing rings, also known as O-rings. It began to appear in the middle of the 19th century when it was used as the sealing element of the steam engine cylinder. O-rings are suitable for installation on various mechanical equipment, and they can seal under the specified temperature, pressure and different liquid and gas media in the static or moving state.