From Madbull, these are fully licensed Noveske style Aluminium outer barrels. Tough, light and high quality; Madbull makes some of the best outer barrels around and they offer them in a broad variety of lengths. A standard M16 has a 20 inch barrel while the standard M4A1 has a 14.5 inch barrel but the beauty of the M16 family is their ability to modify the length with a lot more options then that.
This 10.5 Inch (264mm) barrel is dubbed the 'CQB' barrel as it is a good 4 inches shorter then the carbine length M4A1. Broadly speaking, the shooting performance of dropping your barrel length that much is not that much and yet that 4 inch reduction makes the weapon a lot more compact.
This is a light grey colored barrel with a low profile black gas block and chrome silver gas tube.