Reactive armour is a type of vehicle armour that reacts in some way to the impact of a weapon to reuce the damage done to the vehicle being protected. It is most effective in protecting against shaped charges and long rod penetrators. The most common type is explosive reactive armour (ERA), but variants include self-limiting explosive reactive armour (SLERA), non-energetic reactive armour (NERA), non-explosive reactive armour (NxRA), and electric reactive armour. Unlike ERA and SLERA, NERA and NxRA modules can withstand multiple hits, but a second hit in exactly the same location will still penetrate.