This content is no longer present within PlanetSide 2!
Reinforced Side Armor was a defense module available to main battle tanks and the Lightning. It was unlocked through purchase with Certification Points.
Before the Combined Arms Initiative, tanks would take more damage if hit from a target that was located in an arc to the left or right side of the vehicle. With the update, tank's defences were loaded more into their health pool rather than armour, and the side modifier was removed and only hits to the rear of the tank deal increased damage.
Alongside this update, directional armour buffs such as Reinforced Front Armor and Reinforced Side Armor were removed, and replaced with Flanker Armor. All certifications spent on the ability were refunded.