ISO 3601-1:1988 - Fluid systems — Sealing devices — O-rings — Part 1: Inside diameters,
DIN ISO 3601-1:2013 - Fluid power systems - O-rings - Part 1: Inside diameters, cross-sections, tolerances and designation codes (ISO 3601-1:2012 + Cor. 1:2012)
ISO 6164 O-Ring Bezeichnung Codes Abmessungen - Wissen - Yuyao Jiayuan Hydraulic Fitting Factory