Sassanian body armour - cuirass

[Bashir]

Close up of the Karen knight and the Suren knight on Firuzabad, and examination of some spahbed seals, clearly shows a disk on the knee.
Also, old thread is old

Looks good but where the archaeological evidence?

[Sextus Saturninus]

Are you even looking at the sculptural relief above? Nadeem even puts the evidence in the post you cited. The relief clearly illustrates a Sassanid cavalryman wearing leg armor. Clearly proves it. Also, Renatus above says how Julian, when writing on the cavalry, talks about KNEE COPS. Your question should be answered.

[Bashir]

I see there's a knee cap on the seal.