This is a cutaway of the Radiamic liquid fuel thruster of about 100 pounds thrust. It was designated the C-1, or "Common Engine" by the National Aeronautics and Space Administration (NASA).
The C-1 was developed beginning in 1965 by the Reaction Motors Division of the Thiokol Chemical Corporation as a versatile small liquid fuel auxiliary rocket engine adaptable for a number of launch vehicles and spacecraft control systems. However, NASA decided not to go with a common engine and the C-1 never became operational. This engine was donated to the Smithsonian in 1976 by the NASA Marshall Space Flight Center.