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 18 Inch (467mm) barrel is dubbed the 'SPR' barrel as it is just shy of a full length 20 inch M16. A drop in 2 inches from the M16 standard length means that shooting performance is about the same (superior to standard M4A1) but shaving of a couple of inches makes the rifle a bit easier to work with.
This is a light grey colored barrel with a low profile black gas block and chrome silver gas tube.