From "Monopoly, the World's Most Famous Game" by Philip E. Orbanes. This version replaced the #12 Gold version in the Parker catalog due to the plastics shortage caused by WWII. Buildings were made of Ivoroid instead of the more expensive Bakelite. This is reflected in the model number as well. The model number on Parker's Monopoly versions (through WWII at least) represented the retail price in US dollars. This was an $11 game replacing a $12 game in the catalog.