A4: The Toughest Armor Ever. Titanium for its extreme hardness. Steel for its extreme durability. If you need stopping power, you've come to the right place.The Strength of the A4 The A4 is built to stop the two major threats to an armor plate: fast rounds and high-energy rounds. M193 is a very fast round. It is light and efficient. It cuts like a knife, molding into a cutting projectile on impact, following the path of least resistance. M80A1 delivers very high kinetic energy. Its steel penetrator, aggressive powder load, and heavier weight (being a .308 round) make it more powerful than the M193 at its slower speed. Composite plates, though they may be able to stop this round, still struggle with the payload delivered in backface deformation. These two rounds are archetypal; not only are they serious threats in themselves, but they also capture the effect of a wide range of threats one could face. The A4 is built to stop these rounds, not barely, not sometimes, but with ease. It i...