I keep saying this needs to be some sticky... you will need fittings and tube in the same measurement either imperial or metric. Even in the above it says 16mm is 5/8 - it isn't its 15.875 I think. Stick to the same, be wary of anything quoting both mm and inches, for hardline the OD is critical to prevent leaks.
might sound small but it's enough... you might get lucky and it comes up ok, you might not and the risk is obviously great.