The CZ 805 assault rifle is a modular, multi-caliber design, with an aluminum alloy upper receiver and polymer lower receiver / fire control unit. The magazine housing is a separate detachable unit, which can be replaced in the field as part of a caliber change. The weapon is gas-operated and features a rotating bolt and a manual gas regulator. The CZ 805 also features quick-change barrels, allowing users to change calibers and barrel lengths according to the mission profile. There are short "carbine", intermediate "standard", long "marksman" and heavy "squad automatic" barrels available in each caliber. The Fire control unit includes ambidextrous safety/fire selector switch, which permits single shots, 2-round bursts and full automatic fire. Charging handle can also be installed on either side of the weapon, depending on user preferences. In standard configuration, the CZ 805 will use proprietary 5.56x45 caliber 30-round magazines made of translucent polymer. Other magazine housings will allow use of STANAG or HK G36 5.56mm magazines, as well as various 7.62x39mm and 6.8x43mm magazines.