Constantius II campgate from Siscia, same busts but different.

Hallo to everybody (-1)

Here are some coins minted in Siscia, officina.(delta)SIS..
obverse: fliulconstantiusnobc rev: providen-tiaecaess Bust B4l, RIC VII nr203. This featcher is only visible at this officina.
my question: what is the circled item. An extension of the armor, a chain or something else.

a second

a third : not sure if this is a rectangular shield or not

a normal one

and last: with decoration in the base of the camp gate

Thanks for your answers, feel free to post other pictures from campgate coins of Siscia.

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