Technician Fourth Grade (abbreviated as T/4 or TEC4) 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. Technicians possessed specialized skills that were rewarded with a higher pay grade. These skills could be directly related to combat, such as those skills possessed by a tank driver or combat engineer, or skills possessed by those in support functions such as a cooks or mechanics. Depending on his or her function, he or she might be called upon by an officer to command a group of men for 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.