Typical unit has 1/4“ VCR fitting. Originally I was hoping to find one with Swagelok tube fittings until I understood these connectors better. Swagelok tbe fittings are easy to make but they have one major disadvantage over VCR: while getting a “as new” VCR connection is as simple as replacing a gasket, the entire Swagelok tube fitting (male?) assembly must be replaced. Thus, it would be a poor choice to put a swagelok tube fitting on any reusable, expensive equipment (ie MFCs), unless you have a very good reason.

The one above that has Swqagelok tube fittings does at least have them on NPT adapters so that they can be replaced as they wear out. So if you don't expect to disassemble the machine very often that is probably an okay compromise. If you ever start having problems though and want to troubleshoot it may get expensive and frustrating very fast.