30mm caliber in the context of Autocannon

An infantry fighting vehicle (IFV), also known as a mechanized infantry combat vehicle (MICV), is a type of armoured fighting vehicle, light tank, and armoured personnel carrier used to carry infantry into battle and provide direct-fire support. The 1990 Treaty on Conventional Armed Forces in Europe defines an infantry fighting vehicle as "an armoured combat vehicle which is designed and equipped primarily to transport a combat infantry squad, and which is armed with an integral or organic cannon of at least 20 millimeters calibre and sometimes an antitank missile launcher". IFVs often serve both as the principal weapons system and as the mode of transport for a mechanized infantry unit.

Infantry fighting vehicles are distinct from general armored personnel carriers (APCs), which are transport vehicles armed only for self-defense and not specifically engineered to fight on their own. IFVs are designed to be more mobile than tanks and are equipped with a rapid-firing autocannon or a large conventional gun; they may include side ports for infantrymen to fire their personal weapons while on board.