PURPOSE The purpose of this Aerospace Standard (AS) is to set forth a standardized dash numbering system for O-Rings. It 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.