On 26 September the United Kingdom commissioned its sixth and final Type 45 destroyer. HMS Duncan was laid down in early 2007 and launched in October 2010 at the BAE Systems’ Govan shipyard on the River Clyde. These ships, known collectively as the Daring class, represent to most advanced surface ships in the Royal Navy. The 8,000-ton destroyers each measure 500 feet in length with a beam of more than 50 feet and a top speed in excess of 31 knots. The Duncan and her five sisters are each fitted with the highly capable Sea Viper air-defense system that includes vertically launched Aster-15 and Aster-30 surface-to-air missiles linked to the Type 1045 SAMPSON 3D radar. Also carried are a 4.5-inch main gun and Merlin or Lynx helicopters; the class retains the capability to carry other weapons such as the Phalanx close-in weapon system and Harpoon antiship missiles. The Duncan and the rest of her class have replaced the now-retired Type 42 air-defense destroyers in service.