Emergency Service Ratings (ESRs) from 1948 to 1957 and Emergency Ratings (ERs) from 1957 to 1965. All personnel holding an Emergency Service rating were members of the Naval Reserve subject to activation only in time of war or national emergency. Their specialty letters had a prefix of "ES" added and were different than that of those in regular service. A pruning and absorption or discontinuing of specialty ratings commenced between 1957 and 1964 and nearly all of the remaining specialties were discontinued in 1965. The sole remaining specialty was ESK (ES Specialty (K) – "Telecommunications Censorship Technician"). It was renamed "Information Security Specialist" in 1972 and disestablished in 1974. United States Space Force On 1 February 2021, the United States Space Force established the rank of specialist for paygrades E-1 to E-4. Specifically, the rank of specialist 1 replaced airman basic (E-1), the rank of specialist 2 replaced airman (E-2), the rank of specialist 3 replaced airman first class (E-3), and the rank of specialist 4 replaced senior airman (E-4). Specialist 4 ranks below sergeant. Verbal address for all four grades is just Specialist. On 20 September 2021, new rank insignias for all enlisted guardians, including the specialists, were revealed. These new insignias will replace the U.S. Air Force enlisted rank insignias that have been worn by enlisted guardians since the foundation of the Space Force on 20 December 2019. References External links U.S. Army Enlisted Rank InsigniaCriteria, Background, and Images The Short History of the Specialist Rank by Daniel K. Elder, CSM (Ret), USA Military ranks of the United States Army Enlisted ranks of the United States Space Force United States military enlisted ranks