The Mark 101 Lulu was an air-dropped nuclear depth bomb (NDB) developed by the United States in the 1950s. It utilized a W34 nuclear warhead, with a yield of 11 kilotons. It was deployed by the United States Navy for the purposes of anti-submarine warfare, in five different models, from 1958 until 1971. Weapons were also stockpiled at overseas allied bases under U.S. Marine Corps guard for use by maritime aircraft of NATO allies, notably at RAF St. Mawgan, Cornwall, UK, for use by Royal Air Force Avro Shackleton aircraft, and Dutch Navy P-2 Neptune and P-3 Orion aircraft. The Mk-101 Lulu was replaced by the multi-purpose B-57 NDB in the mid-1960s. The B-57 was a nuclear depth bomb that could also be used by tactical strike aircraft in a land warfare role. The Mk-101 Lulu had a length of 7 ft 6 in, diameter of 1 ft 6 in, and weighed 1,200 lbs. The W34 boosted fission warhead used in the Mk-101 Lulu was also used in several other similar weapons, and a version referred to as 'Peter' was used as a thermonuclear primary in the British Yellow Sun and as 'Python' in the U.S. B28 nuclear bomb.