They aren't so easy to get these days, and are not called UNF or UNC anyway. They are referred to simply by the jaw size in inch fractions, or as "Imperial" sizes. I look after my Snap-On Imperial tools very carefully. They will see me out.
I still think they are easier to recognise.
But then, I am old, brought up on pounds shilings and pence, tons hundredweights and pounds, and miles yards and inches , all good decent Christian units of mensuration that evolved over centuries because they WORKED.
Napoleon invented the metric system only so that France would not use ENGLISH units! A metre was to be one ten-millionth of the distance from the equator to the north pole (or south pole). They got it wrong anyway, and so ALL metric units are bastard sizes as a result, including litres.
In many parts of France they still use pounds weight as a unit, such as a pouind of butter. Slob may know if that is what they do in his area.
CharlesY