These are three Estes Industries B3-6 unflown model rocket motors in a cardboard mailing tube. The "B3-6" signifies that the power of the motors is in the second lowest class (out of seven) established by the National Association of Rocketry. The motors are made of pasteboard and contain non-explosive propellant. A motor is used only once to power a model rocket.
G. Harry Stine, a pioneer in the field of flying rocket models, donated the artifact to NASM in 1973.
Gift of G. Harry Stine