The term grommet slider needs a product drawing to identify the intended joint. A sleeve fitted over a tube and a grommet seated in a panel are different arrangements.
Measure the mating features and use the specified fit range. Do not choose an undersized part simply to make the joint tighter, especially with glass components. Use only assembly aids permitted by the product instructions and compatible with the material.
Measurement accuracy depends on the tool and method, not whether the units are metric or imperial. Confirm temperature, fluid exposure and any pressure requirements, then verify the completed connection.
