The CZ 805 Bren A2 is a gas operated, selective fire weapon, chambered for a standard NATO 5.56x45mm ammunition. Its design was influenced by the Heckler & Koch G36. The CZ 805 was originally developed as a multi-caliber weapon. It modular design enables simple changing of the caliber. This assault rifle can be also converted to use 7.62x39 mm and 6.8x43 mm ammunition. Caliber change is performed by the shooter by simply replacing the barrel, gas-piston unit, breech block and magazine housing. Three barrel lengths are available for each caliber. This weapon was originally planned to be available in three versions - carbine, standard assault rifle and light machine gun / marksman rifle.
The CZ 805 has an aluminum receiver. A number of parts are made form polymers. However soon after its adoption it appeared that this weapon has a number of teething problems. It was criticized by the soldiers as being to heavy, having poor ergonomics and bad balance (which reduces its firing accuracy). Unlike on most modern assault rifles its cocking handle reciprocates while firing and do not stops at its rear position when all ammunition is expended.
An ambidextrous cocking handle can be mounted on either side of the housing. The trigger group is also ambidextrous.
A fire mode selector has "semi-auto", "2-round burst", "full-auto" and "safe" settings. Spent cases are ejected to the right side only, however there is a case deflector, which propels cases from the left-handed shooter.
The CZ 805 assault rifle is normally fed from 30-round capacity magazines. Also there are 20-, and 100-round capacity magazines for this weapon. First production CZ 805s were supplied with transparent magazines, that were interchangeable with the German Heckler & Koch G36 magazines. Two or three of these magazines could be clipped together for rapid reloading. However later the CZ805s were supplied with the standard NATO M16-type magazines.