class or private in authority, but drew additional pay in relationship to the specialist level possessed on top of their base pay. The classes only indicated competency, not authority, and a specialist did not outrank another man of his respective non-specialist rank. Officially, specialists wore the single chevron of a private first class because no special insignia was authorized to indicate their rank. Unofficially, a specialist could be authorized, at his commander's discretion, to wear one to six additional rockers (one rocker for sixth class, and a maximum of six rockers for first class) under their rank chevron to denote specialty level. Such insignia was commercially available through catalogs or the base Post Exchange (PX) and could also be ordered with inset trade badges. Technician (1942–1948) On 8 January 1942, the rank of technician was introduced to replace the private/specialist rank, which was discontinued by 30 June 1942. Initially, this gave technical specialists more authority by grading them as non-commissioned officers. However, confusion and lowered morale among senior NCOs led to the Army reversing this stance in late 1943, after which technicians no longer held non-commissioned officer status. Beginning 4 September 1942, technicians wore a block "T" insignia under their chevrons for easier identification. Technicians were addressed the same as the corresponding non-commissioned officer at the same pay grade: a technician fifth grade was addressed as corporal, a technician fourth grade as sergeant, and a technician third grade as staff sergeant. The technician ranks were discontinued in 1948. Specialist (1955–present) On 1 July 1955, four grades of specialist were established: Specialist third class (E-4 or SP3), specialist second class (E-5 or SP2), specialist first class (E-6 or SP1), and master specialist (E-7 or MSP). The insignia was yellow on a dark blue background. It was the same smaller size as women's NCO stripes—to differentiate specialists from NCOs, the stripes were the same shape as NCO stripes—but were inverted to distinguish them, and the General Service Army Eagle was set in the center. The senior specialist ranks of SP2 (E5), SP1 (E6), and MSP (E7) were indicated by one, two, or three yellow arcs over the eagle, respectively. In 1956 the Army Green uniform was adopted. The enlisted stripes were changed from yellow on a blue backing to Goldenlite Yellow on a green backing. The specialist insignia was redesigned to be larger, broader, and more rounded. In 1958 the DoD added