Germany's Rheinmetall and Austria's Steyr Mannlicher have partnered to manufacture and market a new and modular military assault rifle.

The RS556 -- 5.56x45 mm -- is based on Steyr Mannlicher's STM556, which Steyr Mannlicher first unveiled in 2012. It fires NATO's standard 5.56 mm rounds.

It has a standard 16-inch barrel and features a 30-round magazine. It weighs just over nine pounds and has an adjustable-length lightweight stock.

According to Rheinmetall and Steyr Mannlicher, the weapon's barrel can be quickly and easily exchanged for longer and shorter barrels for mission customization. The rifle can also be fitted with various optics and night observation devices or laser light modules.

The weapon is seen as a possible candidate to replace the German Army's standard G36 assault rifle beginning in 2019.