The Mark 14 nuclear bomb was a 1950s strategic thermonuclear weapon, the first deployed solid-fuel hydrogen bomb. It was an experimental design, and only five units were produced in early 1954. It was tested in April 1954 during the Castle Union nuclear test and had a yield of 6.9 Mt. The bomb is often listed as the TX-14 (for "experimental") or EC-14 (for "Emergency Capability"). It has also been referred to as the "Alarm Clock" device though it has nothing to do with the design by the same name proposed earlier by Edward Teller and known as the Sloika in the Soviet Union. The fusion fuel used by the bomb was 95% enriched Lithium isotope 6 lithium deuteride, which at the time was a scarce resource, this scarcity being chiefly responsible for its limited deployment. The Castle Bravo test showed that unenriched Lithium isotope 7 functioned as well for nuclear fusion reactions as isotope 6. The Mk-14 bomb had a diameter of 61.4 inch and a length of 222 in. They weighed between 28950 and 31000 lb, and used a 64 ft parachute. The version tested at Castle Union used a RACER IV primary. 5 Mt of its total yield came from fission, making it a very "dirty" weapon. By 1956, the components of all five of the produced Mk-14 bombs had been recycled into Mark 17s.