Contains two twin 40mm Bofors Mk.IV on Hazemeyer mounting.
This naval anti-aircraft weapon was first conceived by the Dutch Navy, and developed later by the British after the fall of Holland. Well in advance on its time, the mounting was gyro stabilized with Hazemeyer system, and entered service in late 1943 with the Royal Navy destroyers of the 5th emergency flottilla. Sloops of the Black Swan and modified Black Swan classes were also equied with this weapon.
While very efficient the Hazemeyer system suffered from difficult maintenance, and was subject to sea damage.