T-51b powered Infantry armor represented the peak of armored infantry technology before the Great War, developed in the laboratories of the West Tek Research Facility. At the end of the Anchorage Reclamation in January 2077, the armor had become standard issue for American soldiers in the Army's Mechanized Cavalry Regiments. Now, only the most technologically advanced factions with ties to the pre-Great War American military or federal government, such as the Brotherhood of Steel or the Enclave, have access to this type of Power Armor. The Brotherhood of Steel does not possess the technology required to manufacture new suits of power armor and relies only on repaired and refurbished pre-Great War suits. Among the soldiers of the Enclave, this Power Armor is seen as obsolete, as it was replaced by the Enclave's advanced power armor and advanced power armor Mk II models, though it should be noted that it is still used by soldiers of the Enclave who have not been issued the newer armor, most likely due to slow production rates for a faction that is still quite small and possess only limited resources in the post-atomic world.