Armor was a new technology in World War One.  Introduced by the Germans, it took the allied French and British forces by surprise.  The Americans came into the world war in the spring of 1917 and had to play catch up.  US armored troops used the French Renault tank on the battlefield.  Enlisted ranks American Tank Corp personnel wore this collar badge (pictured right).  One inch round, die struck in bronze and darkened.  Artwork shows an early WW1 tank above the two dragons.  This insignia has a threaded post on the reverse side with a threaded keeper for attachment to the uniform. 

This is the Rare first pattern officer ranks collar badge.  It is an early style tank oriented as facing you.  1 inch tall by 1 1/4 inches across in size.  Pinback with a simple hook pin catch.  Made for wear on the officer's green wool field uniform.