Lamellar Doubler?

[Osyr]

I'm constructing lamellar armor (Late Roman era), what evidence is there for the shoulder protection? Did they use a round doubler like on a squamata, or a squared sided one like on earlier hamata?

[Flavivs Aetivs]

The few examples of Roman lamellar I've heard of point to a circular shoulderpiece (no doubler, in other words). Similar to squamata but made of rigid lamellar plates.