This is a commercial copy of the Gemini IX mission patch. Although the early Gemini missions were numbered with Arabic numerals, later flights used Roman numerals.
Gemini IX, launched on June 1, 1966, was the seventh human flight in Project Gemini, NASA's second human spaceflight program. Eugene "Gene" Cernan and Thomas " Tom" Stafford were the astronauts. Gemini IX achieved the third rendevous with another spacecraft in the program, an unpiloted Agena target vehicle which had been launched the same day. Additionally, Cernan conducted extra-vehicular activity.
This replica was made for commercial sale. Mance Clayton donated it to the National Collection in 1982.