WWI, U.S. ARMY, SIGNAL CORPS, AVIATION SECTION, COLLAR DISK, TYPE 1 Very nice original Air Service Overseas collar disc as requested by the AEF Chief of Air Service on April 18 1918, and approved by the War Department. This particular collar insignia was for the Aviation Section of the Signal Corps, and was only authorized for approximately 80 days. Type 1 Collar Discs were issued from 1910 until 1926. They were primarily issued in a bronze finish and used a screw nut to attach to the uniform. The left collar disc could contain the Regiment number and Company Letter, or number/letter combinations for special assignments. The left disc could also include the regiment number and company letter. To simplify disc production as mobilization for WW1 progressed, the Regiment number was moved to the right disc with the Company letter on the left disc. As mobilization continued and the number of units increased, both letter and number were dropped. Six background patterns have been identified but are considered manufacture variations. Army Regulations issued on October 14, 1921 stated that collar disks were to be bronze on service uniforms and gilt on white uniforms. On November 25, 1924 the bronze disks were dropped.