With the live coverage of the war in Ukraine from media all around the world, it is easy to run into photos or videos of Russian tanks. In Ukraine, Russia’s main battle tank (MBT) is the T-72, but they also deployed some T-80s and some T-90s. By carefully looking at these units, it can be noticed that Russian, but also Ukrainian tanks are equipped with small blocks all around their armour. These blocks are an additional defensive armour, which serves the purpose to protect the tank and its crew from anti-tank weapons. This additional armour is called Explosive Reactive Armour (ERA).