Yes with hard tubing as usually the fitting compress's down onto the tube and / or secures it from the outside, rather then having something hold it from the middle as you likely will see with soft tubing, so yeah its the OD of the fitting that is important. Most 16mm OD fittings should fit, but buy 1 or 2 and try them first before committing. Can be some odd quirks, mainly with how each brand measure, but on the whole, should be okay.