This is a 100-pound thrust Gemini Orbital Attitude Maneuvering System (OAMS) thruster. OAMS thrusters provided thrust for the U.S. Gemini spacecraft to rendezvous with the Agena target vehicle, controlled the spacecraft in orbit, enabled the separation of the Gemini from the second stage Titan launch vehicle and inserted it into orbit, and provided abort capability. The OAMS consisted of 100-pound thrusters to maneuver the craft axially, vertically, and laterally; 85-pound motors for forward and rearward motions; and 25-pound thrusters to control the Gemini craft in its pitch, yaw, and roll axes. Four 100-pound thrusters were situated at equidistant places around the middle of the crew cabin.

Gemini OAMS motors used the hypergolic (self-igniting) propellants, which made the system simple and reliable and eliminated the need for a separate igniter. In February 1962, McDonnell Aircraft Corporation, the main contractor to NASA for the Gemini spacecraft, awarded a subcontract to North American Aviation's Rocketdyne Division for the development of the OAMS thrusters. Qualification tests on these systems were completed in August 1965, and they performed satisfactorily in all Gemini missiions until the conclusion of the program in November 1966.

McDonnell Douglas donated this truster to the Museum in 1968.