I suspect that there is some confusing use of terms going on.
To me, a "NATO can" is the same thing as the Wavian metal fuel can, and those look like this:
The distinctive features of this design are the weld seam that goes around the middle from top to bottom and back; and the sort-of oval opening that is offset to one side and is closed and sealed with lever. As best as I can piece together these used to be known as "gerry cans" because their design originated in Nazi Germany, The design has since been adopted by most all of Europe regardless of which side of the Iron Curtain the adopting country was on. Probably because the Nazis left them scattered all over the continent and it was easier to adopt a good design than to try to better it when there were so many of them floating around.
The Sceptre fuel can, which I gather some call a "NATO fuel can", but the only military that I've witnessed to use them is the U.S., looks like this:
The distinctive feature of these cans is that they are a rotary molded plastic can. They use a thread-on cap and nozzle.
The old school US metal fuel can were made by Blitz (& I'm sure others) and they look like this:
The two distinctive features of these cans is the screw-in cap and nozzle, and the pinch-weld seam around the bottom.
My own experience has been that the Blitz cans are a waste of time; that pinch-weld seam is where they notoriously fail and leak, don't bother.
The Sceptre cans are a good design, but their threaded cap & nozzle connection can fail them.
I have seen the Wavian cans take punishment beyond belief and not leak. With the Swiss nozzle they will empty their fuel faster than you'd think was ever possible and should be the can of choice.
