O-rings and X-rings are both types of seals commonly used in various industrial and mechanical applications. Both seals have a circular shape and are made from materials such as rubber, silicone, or polyurethane.O-rings, also known as toric joints, are the most commonly used seals due to their simple design and cost-effectiveness. They work by creating a barrier between two surfaces, preventing the escape of fluids or gases. O-rings are typically used in applications where the pressure is less than 1500 psi and the temperature is below 200 degrees Celsius.www.bdseals.com/Rubber-orings.html