Original: Disguised in a replica of Great Seal of the United States carved in wood, in 1945 Soviet school children presented the concealed bug to U.S. Ambassador as a "gesture of friendship" to the USSR's World War II ally.
Simplified: On August 4, 1945, Soviet school children presented the bugged carving to U.S. Ambassador Averell Harriman, as a "gesture of friendship" to the USSR's World War II ally.