30mm DS30M Mark 2 Automated Small Calibre Gun
The 30mm DS30M Mark 2 is a ship-protection system made by MSI-Defence Systems consisting of a 30mm Mark 44 Bushmaster II cannon on an automated mount. It was designed to defend Royal Navy frigates from fast inshore attack craft armed with short-range missiles, rocket-propelled grenades, machine guns, or explosives.
Source: Wikipedia — 30mm DS30M Mark 2 Automated Small Calibre Gun (CC BY-SA 4.0)