The CR 21 is a modern bullpup assault rifle of South African origin. It was designed to replace the Vektor R4 (Galil) rifle in South African service, but never left the prototype stage. The iconic and futuristic exterior of the CR 21 hides a plain and proven R4 rifle inside. Although being a more modern design, the CR 21 had few advantages over the R4 while introducing some new drawbacks.

The CR 21 is based on the Galil rifle and most internal parts are either exchangable or very similar. The CR 21 is gas operated and uses a long stroke gas piston and a rotating bolt. Externally the CR 21 looks very different since it has a bullpup configuration and uses a large plastic housing. The charging handle is located at the front left side, while the ambidextrous fire selector is located at the rear. A proprietary non-magnifying optical sight with illuminated reticle is fitted as standard. There are no iron sights.

The CR 21 fires the 5.56x45mm M193 round from standard 35 round Galil magazines. The CR 21 is a select fire rifle with a rather low cyclic rate of fire of 700 rpm or lower. The maximum effective range is quoted as 400 meters.

The CR 21 was tested but never acquired by South Africa. Small batches of CR 21 were acquired by several South American nations. These may have been acquired for trails only, but are believed to be in active use with special units.