Special Operations Augmentation (SOA) provided cover for the clandestine Studies and Operations Group (SOG). The recipient was a member of SOA Command and Control South, 5th Special Forces Group Airborne. This group formed the core of SOG ground missions. SOG ran highly classified sabotage and psychological and special operations in North and South Vietnam, Laos, Cambodia and southern China.
The cover was sent Registered mail from Thailand in September 1970. The rubber stamp marking on the cover front simply reads "Air Mail" in English and Thai script.