This is a Sources Sought notice for the sustainment of the Radioisotope Identification Detector (RIID) Repair Program, covering engineering services, testing, repairs, and technical support. The Air Force seeks contractors capable of repairing or maintaining approximately 375 RIID units over a 5-year period. Work includes maintenance, repairs, calibration, software updates, and updates to training materials and technical manuals. No specific budget amounts, submission timelines, or performance location are mentioned in the description. Responses will be used for market research and planning purposes.