This is an unflown Rocket Development Corporation B4 model rocket motor. The "B4" signifies that the power of the motor is in the second lowest class (out of seven) established by the National Association of Rocketry. The motor is made of pasteboard. The non-explosive propellant has been removed from it. A motor is used only once to power a model rocket.
G. Harry Stine, a pioneer in the field of flying rocket models, donated it to NASM in 1973.
Gift of G. Harry Stine