This is an original Vietnam War-era patch for the The "U.S. Naval Support Facility - Cam Ranh Bay". Four inch diameter patch is no-glow front & back, full factory embroidered. Unissued, but does have tiny bit of fraying on the edge in the 7 o'clock position, like it was trimmed just a hair too closely (see last pic).

U.S. Naval Support Facility in Cam Ranh Bay was a major naval base and logistics facility in Khánh Hòa province, Vietnam. Cam Ranh Bay is a deep-water bay in the South China Sea that is up to 164 feet deep. The U.S. military built the facility in 1965 and used it until 1972.