George Washington, America's first spymaster, considered the accumulation of secret intelligence one of the most important weapons in winning the war.  In his term as Washington's Secretary of State, Thomas Jefferson devised a cylindrical cypher wheel, an ingenious and secure method to encode and decode messages.    
Mount Vernon's all wood version of the secret decoder wheel features 12 cylinders which can relay a 12-letter message. Instructions included.  
Cypher wheel is approximately 6" x 2 ½".  

A great educational toy for boys and girls ages 5 and up, but not recommended for children under 3.