Technician Fourth Grade (officially abbreviated as T/4) was one of three United States Army technician ranks established on January 8, 1942 during World War II. Those who held this rank were often addressed as Sergeant, as they shared the same pay grade. Technicians possessed specialized skills which were rewarded with a higher pay grade. These skills could be directly related to combat, such as a tank driver or combat engineer, or be a support function such as a cook or mechanic. Depending on their function, they might be called upon by an officer to command a group of men in doing a specific task, they were non-commissioned officers as were sergeants. Initially they shared the same insignia but on September 4, 1942, the three technician ranks were distinguished by a block "T" imprinted below the standard chevrons. Unofficial insignia using a technical specialty symbol instead of the T were used in some units.