Muzzle flash is the light — both visible and infrared — created by a muzzle blast, which is caused by the sudden release and expansion of high-temperature, high-pressure gases from the muzzle of a firearm during shooting. Both the blast and flash are products of the exothermic combustion of the propellant (gunpowder), and any remaining unburned powders reacting with ambient air. The size and shape of the muzzle flash is dependent on the combustion energy of propellant being used, the amount of combustible ejecta remaining, and any devices attached to the muzzle (such as a flash hider, suppressor or muzzle shroud).