This is the bonus kit that comes with the Bismarck kit.
The 38 cm S.K. C/34 Naval gun was developed by Germany mid to late 1930s. It armed the Bismarck-class battleships and was planned as the armament of the O class battlecruisers and the re-armed Scharnhorst-class battleships. Six twin-gun mountings were also sold to the Soviet Union and it was planned to use them on the Kronshtadt-class battlecruisers, however they were never delivered. Spare guns were used as coastal artillery in Denmark, Norway and France. One gun is currently on display at Møvig Fortress outside Kristiansand.
The data given is according Krupp datasheet 38 cm S.K.C/34 e WA52-453(e). This gun was mounted in pairs in the Drh.L. C/34e turret which allowed elevation from -5° 30' to +30°. Each gun had an individual cradle, spaced 3.5 metres (11 ft) apart, but they were normally coupled together. In general the turret was hydraulically-powered, but the training gear, auxiliary elevation, auxiliary hoists and some loading gear was electrically powered. The turrets weighed 1,048 tonnes (1,031 long tons; 1,155 short tons) to 1,056 tonnes (1,039 long tons; 1,164 short tons), rested on ball bearings on a 8.75 metres (28.7 ft) diameter track, could elevate 6° per second and traverse 5.4° per second. The guns were loaded at +2.5° and used a telescoping chain-operated rammer. According to German manuals the required permanent capacity for the loading equipment for ammunition was 2.5 shells per minute. During testing period at the Baltic Sea the AVKS Report states an output of the ammunition delivery system up to 3.125 shells per minute. Under battle conditions Bismarck averaged roughly one round per minute in her battle with HMS Hood and Prince of Wales.
Sixteen guns were used for the Bismarck and Tirpitz and six were ordered for the Gneisenau when it was to be re-armed in 1942. Six were intended for each of the O class battlecruisers, but it is uncertain how many of these last were actually delivered. Six mountings with twelve guns were sold to the Soviet Union who planned to use them on two Kronshtadt-class battlecruisers, but these were never delivered. Surplus guns were used as coast defense guns.