An Operational Requirement (OR1142) was issued in 1955 for a thermonuclear warhead for a medium-range ballistic missile, which became Blue Streak. This was revised in November 1955, with "megaton" replacing "thermonuclear". Orange Herald could then meet the requirement. Codenamed Green Grass, the unsuccessful fusion boosting was omitted, and it used Green Bamboo's 72-lens implosion system instead of Orange Herald's 32. This allowed the amount of highly enriched uranium to be reduced from 120 to 75 kg. Its yield was estimated at . It was placed in a Blue Danube casing, and became known as Violet Club. Road transport of the weapon was hazardous. As a safety measure 120,000 steel ball bearings were used to fill a cavity inside the core and keep the fissile components apart. In an accident, the steel bung was removed and the ball bearings spilled on the floor of an aircraft hangar, leaving the bomb armed and dangerous. About ten were delivered.