These barrels can be used on IJN Kongo and Fuso class battleships and for Agano class cruisers. They were built by Vickers in England as secondary hull mounted guns for Kongo. Later the Japanese designed there own identical looking version. Mounting on battleships the elevation can be set up as high as 30 degrees but on Agano elevation was able to go to 55 degrees. Extra guns had been manufactured which as a result of surplus were used on the four Agano class cruisers which carried these in twin mountings.

The set comes with 16 barrels. Instructions gives you a drill bit size best used to receive a barrel. Further it provides a couple photo examples of hull mounted barrels.