Midstate Plastics offers thousands of O-Rings in stock. To help find the O-Ring you are looking for, see the Specification Chart Below. To determine the size, there are two dimensions used to describe O-Rings; Inside Diameter (ID) and Cross-Sectional Diameter (CS). These are the figures used in determining sizes in the Specification Chart below. If you cannot find the O-Ring you are looking for or wish to have a custom O-Ring made, please contact us for a quote & design.