What is a self-propelled anti-aircraft gun?

referred to as "self-propelled anti-aircraft gun", it is an anti-aircraft gun that combines the aiming and launching system with the vehicle chassis and can move by itself. It is mainly used to annihilate low-altitude and ultra-low-altitude targets and cover marching and fighting troops. It can also be used to destroy ground targets if necessary. According to caliber, there are small caliber and medium caliber self-propelled anti-aircraft guns; According to the self-propelled way, there are crawler and wheeled self-propelled anti-aircraft guns; According to the function, there are all-weather and non-all-weather self-propelled anti-aircraft guns.