Muscle Armor effectiveness

[Flavivs Aetivs]

The Greek Spolas, which we're fairly certain was made of leather, is around 2 inches (5cm) thick to have the equivalent protection of a bell cuirass or muscle cuirass of bronze.

A cuirboulli or leather Musculata would be useless unless it was the same thickness, which would make it both heavier and more expensive to produce than the equivalent cuirass in iron.