Composite armor boosts the armor of all tank units on the battlefield. It increases the survivability of Crusaders (+40%) and Paladins (+20%). The modern-day composite armor consists of multiple layers of metal alloys, layered in between other substances, usually ceramics. In Zero Hour, despite the tooltip change, the effect still remains the same, at least for patch 1.04 (i.e. still + 40% for crusaders and + 20% for paladins).