This Aerospace Standard specifies the inside diameters, cross-sections, tolerances, and size identification codes (dash numbers) for O-rings used in sealing applications and for straight thread tube fitting boss gaskets. The dimensions and tolerances specified in this standard are suitable for any elastomeric material provided that suitable tooling is available. This standard is intended to be used in the preparation of Company, Military, or other Standard Drawings for O-Rings. Each dash number, which should be appended to an appropriate Drawing or Standard number, identifies one nominal size O-Ring only. No attempt is made in this AS to indicate which of the O-Ring sizes listed under this system should be included in any particular Standard Drawing. Its only purpose is to standardize O-Ring sizes and dimensional tolerances and the means of identifying them dimensionally.