The ARKRAY febrile S.typhi AG set H&O is a Widal Test kit that contains Salmonella typhi 'H' and 'O' antigens used to detect the presence of antibodies against Salmonella typhi in a patient's blood, which helps in the diagnosis of enteric fever (typhoid fever). The antigens are prepared from specially selected bacterial strains, are stained, and are supplied with controls and instructions, providing uncompromised sensitivity and uniform clump formation for accurate results.