This is a bag, found inside LM #2 during a 2016 restoration, for that lunar module's Alignment Optical Telescope. The Apollo Lunar Module (LM) was a two-stage vehicle designed by Grumman to ferry two astronauts from lunar orbit to the lunar surface and back. The upper ascent stage consisted of a pressurized crew compartment, equipment areas, and an ascent rocket engine. The lower descent stage had the landing gear and contained the descent rocket engine and lunar surface experiments.
LM 2 was built for a second unmanned Earth-orbit test flight. Because the test flight of LM 1, named Apollo 5, was so successful, a second mission was deemed unnecessary. LM-2 was used for ground testing prior to the first successful Moon-landing mission. In 1970 the ascent stage of LM-2 spent several months on display at the "Expo '70" in Osaka, Japan. When it returned to the United States, it was reunited with its descent stage, modified to appear like the Apollo 11 Lunar Module "Eagle," and transferred to the Smithsonian for display.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.