Metric rubber grommets use metric dimensions, usually millimeters. The unit system does not by itself make a measurement more accurate; tools, method and tolerances determine measurement quality.
Record the mounting opening, panel thickness and cable or tube dimensions. Compare the groove, passage and flange with the product drawing. Keep sufficient precision when converting from inch measurements.
Choose the compound for the actual temperature and exposure. For custom manufacture, provide a drawing or existing sample and agree on tolerances and acceptance criteria. Verify fit before production rather than relying only on nominal size.
