The equipment was brought back to the UK and in 1984 was refurbished by BMARC at Faldingworth in Lincolnshire. The Oerlikon 35mm twin cannon is a towed anti-aircraft gun made by Oerlikon Contraves (renamed as Rheinmetall Air Defence AG following the merger with Rheinmetall in 2009).
The Oerlikon twin-gun uses a 35mm autocannon, which were originally designated 353 MK and are now designated as KD series. The same KD series 35mm cannons are used in the Leopard tank-based Gepard and T-55 based Marksman self-propelled anti-aircraft guns. The ammunition containers are on each side of the cradle and rotate with it. Each fully-loaded ammunition container holds 56 rounds. The ammunition is reloaded in seven-round clips from the reloading container and passed through the upper mount trunnions to the cannon.
The sighting equipment consists of a MBDA sight Type GSA Mark 3, a ground target sight mounted on the MBDA sight housing and an optical alignment sight. The target range is the only parameter to be adjusted in action on the MBDA sight.
This twin-barrel 35mm gun has an Fire Control Unit Skyguard that detects and tracks air targets up to 20km and computes firing data. The first prototype of this was completed in 1959 under the designation 1 ZLA/353 MK, which was renamed GDF-1. In 1980, the GDF-002 model was introduced. More then 2,000 guns were produced and sold in approximately 30 countries.
A typical battery of GDF would consist of two 35mm anti-aircraft twin guns, each with a power supply unit and fire control unit. The guns are controlled by a single Skyguard fire control radar. During a regular mission the 35mm guns are controlled by a fire control unit, but they can also be operated in local mode by the gunner and the two gun loaders, where the gunner is using a joystick for control and a sight for aiming. A hand pump is also fitted and when it is used the weapon can be brought into action in 5 minutes.