The Rarden is a late Cold War era 30mm autocannon of UK origin. It was developed in the 1960's to arm the next generation of armored fighting vehicles. The 30mm caliber was chosen since it was expected that that in the 1970's Soviet armored vehicles would have an armor thicknes of up to 40mm RHA. The Rarden was design for vehicle use and unlike most autocannon it has not been in an anti-aircraft mount since it lacks the volume of fire for that role.

The Rarden is a magazine fed autocannon that uses a long recoil mechanism. The cases are ejected forwards and toxic fumes cannot enter the vehicle. The Rarden uses three round magazines that are inserted into the side. The barrel is long and thin and is made out of high strength steel. A vibration damper is fitted within the barrel sleeve to maintain the level of accuracy. The Rarden uses the 30x170mm round that was developed for the Oerlikon KCB (HS 831), but the ammunition types are not interchangeable since new KCB ammunition uses a steel case instead of a brass one.

The Rarden fires the 30x170mm round at a cyclic rate of fire of 90 rpm. The three round magazines are manually loaded with the feed mechanism accepting two magazines at the same time. The low volume of fire is offset by its high degree of accuracy. Waste of ammunition is also reduced. The 30mm ammunition range includes high explosive rounds and armor piercing discarding sabots that will pierce the armor of nearly any vehicle but tanks.

The Rarden is used on various vehicles of UK origin. The design allows it to be fitted into small vehicles such as the Fox 4x4 armored car and Scimitar tracked reconnaissance vehicle. The most common application is the Warrior mechanized infantry combat vehicle. The Rarden has not been used on foreign vehicles