This is a model of unknown scale of the Sparrow II, a medium-range air-to-air missile which the U.S. Navy began developing in 1955. Due to technical problems, the Navy cancelled the project the following year. The Royal Canadian Air Force then continued development of the missile for possible use on its Arrow fighter, but technical problems with this project forced its cancellation in 1958. Douglas Aircraft made and donated this model to NASM in 1958.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.