The Defense Health Agency intends to award a sole source firm fixed price purchase order to Rees Scientific Corporation for on-site calibration, annual preventive maintenance, and repair of its installed environmental monitoring system. The work will be performed at the U.S. Naval Hospital Okinawa, including its outlying clinics and the Armed Services Blood Bank Center. The period of performance includes a base year from October 1, 2026 through September 30, 2027, plus four one-year option periods extending through September 30, 2031. This notice is not a request for competitive quotes, and no solicitation exists, but interested parties may submit a capability statement to demonstrate their ability to provide the required services. The government will use responses only to decide whether to compete the requirement.