These are two burnt Model Products Corporation model rocket motors. They are made of pasteboard and contain non-explosive propellant. They were placed in a small fire of newspapapers in 1970, evidently to prove that they would not explode. Each motor is used only once to power a model rocket. G. Harry Stine, a pioneer in the field of flying rocket models, donated them to NASM in 1973.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.