They changed the molds for jugs every now and then... so you think you might have 2 or 3 similar jugs... look carefully... a different curve or a different diameter are more often than one thinks.
Look carefully at the shape of these 3 jugs (don't look at the bakelite parts, just the aluminium):
But let's come back to the flatheads!
To own a flathead is not everybody's chance... and to date a flathead is not an easy task.
Someone contacted me from Argentina. Her mother let a Brevetti Robbiati flathead be shipped in 1957!
There is one give away... if you are lucky to have the original jug.
The first jugs were rounder than the later ones.
One can see it very well on the patent:
You don't come across these often.
In the last few years, i have seen 2.
Here are how the early flathead jugs looked like:
After that came the more triangular shaped jug:
While this one appears to me like an hybrid ... not round, not triangular... Hybrid.