Armstrong's Apollo 11 Backup Suit

Three space suits were made for each Apollo astronaut assigned to a flight: a training suit, a backup suit, and a primary (flight) suit. The flight suit, of course, is the one which was worn on the actual flight. Many of the space suits displayed by museums around the country are the backup or training suits, with the Smithsonian retaining most of the flight suits.

Armstrong Air & Space displays Armstrong's backup suit.

I have a number of resource regarding the Apollo spacesuit.

Additional information on the various parts of the Apollo space suit can be found in the "Extravehicular Mobility Unit" chapter of the Biomedical Results of Apollo.