First unveiled in 1997, the rifle utilises the bullpup layout. This enables the rifle to be as short as a typical carbine, whilst still retaining the muzzle velocity of longer assault rifles. However, this makes the CR-21 only capable of being fired from the right hand.
Internally, the CR-21 uses a slightly modified version of the Kalashnikov action found in the R4 assault rifle, which is known for its reliability and relatively low weight. The rifle also makes significant use of high-impact polymer, with the only exposed metal part on the rifle being the front of the barrel with its integral flash suppressor. Both of these result in the rifle having a low loaded weight, of 3.72 kg (8.2 lbs). The CR-21 comes standard with a 1X magnification optical sight with an illuminated reticle that does not require batteries. This sight is mounted on a sight rail, allowing easy removal and attachment, as well as the use of a range of different sight options. The forward handgrip has been specially designed to be easily removed and replaced with a grenade launcher similar to the M203 grenade launcher. Finally, the stock has a built-in compartment which stores a cleaning kit for the rifle, removing the usual need for the soldier to carry this separately.
A CR-21 carbine was said to have been developed by Vektor. Both of their 35-round magazines are based from the R4/Galil rifles.