Mark 7 (nuclear weapon)
Mark 7 was the first tactical nuclear weapon deployed by the United States, with a variable yield. The streamlined case could be carried externally on fighters as well as internally in bomb bays.
As a bomb, the Air Force B-45 Tornado, B-57 Canberra, F-84, F-100 Super Sabre, and F-101 were certified to carry it (as well as, presumably, the heavy bombers), and the Navy's A-1 Skyraider, A-3 Skywarrior, F2H, F3H-2N, and FJ-4B.
Packaged as a warhead rather than a gravity bomb, the Navy used it on the BOAR (Bureau of Ordnance Atomic Rocket or Bombardment Aircraft Rocket), and the Mk 90 Alias Betty, an ASW depth charge for the S2 and P5.
Known as "Thor", it was lighter in weight than the Mark 5, at approximately 772kg/1700 lb. The bomb was 775mm/30.5 inches in diameter and 4.6 meters/15 feet 2.5 inches long. Between 1700 and 1800 were produced between 1952 and 1963, and it was retired in 1967. 
It used an implosion system with 92 detonators, arranged around two fissionable hemispheres. A levitated pit could be inserted in flight. Available yields were 8, 19, 22, 30, 31 and 61 Kt. Late versions had a Category A Permissive Action Link.
- Mark 7 Nuclear Bomb, Globalsecurity
- Carey Sublette (14 October 2006), "Complete List of All U.S. Nuclear Weapons", Nuclear Weapons Archive
- Restricted Data Declassification Decisions 1946 to the Present, U.S. Department of Energy, 1 January 2001, RDD-7