The performance of an armor plate is dictated by its material composition, which determines its protection level and weight: Armor Plate - an overview | ScienceDirect Topics

Armor plates are rigid inserts designed to provide ballistic protection against high-velocity threats, primarily rifle rounds, by absorbing or deflecting kinetic energy. While historical "plate armor" utilized simple steel, modern ballistic technology relies on complex material science to balance extreme protection with wearer mobility. Core Materials and Construction