the field and a shock-mitigating container for parachute delivery. Development began June 1960. Because much of the weapon would be different from the XW-54 warhead, it was proposed that the warhead be given its own unique mark designation, such as TX-58 (later used for the Polaris A-3 warhead), but the decision was made to retain the existing mark number. The weapon was delayed until August 1963 due to issues with the timer. These included premature firing of the timer and issues with bearing materials. An interim Mk 54 Mod 0 weapon (now called the B54-0) was put into production in April 1963. Drop tests for this weapon were conducted at velocities up to vertical and horizontal without damage. Production of the B54 Mod 1 SADM began in August 1964. The weapon was diameter, long and weighed , and included the warhead, fuzing and firing system with a mechanical timer, ferroelectric firing set and a sealed housing. The body was constructed with aluminium forgings and moulded fibreglass, and foam-rubber insulation was used between the warhead and case. Dials were illuminated with a tritium-phosphor paint for easy night-reading. A housing for underwater emplacement was provided which included external controls. The B54 Mod 2 started production in June 1965. The weapon was the same size as previous mods, but now weighed . This may be the highest yield boosted version of the weapon. Design The weapon was based on the Scarab device, which descended from the Gnat device. Scarab was also used as a primary stage in the thermonuclear weapon test Dominic Nambe. Warhead Configured in the Davy Crockett role, the weapon contained two sets of fuzes: a radar based fuze set for a airburst and a capacitance based fuze set for airburst. These fuzes represented the high and low airburst modes of the weapon. The device contained of high explosives. Some sources give the yield for the Mod 0 as and the Mod 2 as , but declassified warhead development documents indicate the only difference between these two warheads was the environmental sensing devices used and that the warheads were field convertible, suggesting the weapons had the same yield. Official documents give the yield as when configured in the XM388 round for the Davy Crockett. It has been alleged that the British "Wee Gwen" warhead was a copy of the W54. Though never put into production, Wee Gwen was to contain of