This 1 inch diameter lapel pin was the emblem of Space Shuttle Mission STS-4, the final orbital test of the space shuttle.

The pin is made by AB Emblems, the NASA contractor for mission emblems.

Look for the embossing on the back of the pin:

Columbia IV
NASA
ABemblem.com

to make sure you are getting the NASA authorized version of the pin.

The Final Space Transportation System research and development flight. In addition to classified Department of Defense payload, cargo included first Get Away Specials, (G-001) which contained nine experiments from Utah State University; first commercial experiment involving Continuous Flow Electrophoresis System (CFES); Monodisperse Latex Reactor (MLR); Induced Environment Contamination Monitor (IECM), which was deployed, and two Shuttle Student Involvement Program (SSIP) experiments.