Cowboys in armour?

What an array of suits of armour!  This photo was taken at Hotel des Invalides in Paris, during the 'pilgrimage' to Napoleon's tomb.

Suits of armour at Hotel des Invalides

Presumably the smallest were for training the boys to fight in armour.  Not particularly surprising I suppose.

But then I saw this metal hat, in a shape that is almost reminiscent of a cowboy's ten-gallon hat.

Interesting armoured hat

Presumably all the little fittings were there for a reason, along with the curved shape of the brim on the left-hand side.