or Radiological Emitting Device.  Also called a "hidden sealed source." An RED is a terrorist device intended to expose people to significant doses of ionizing radiation without their knowledge. Constructed from partially or fully unshielded radioactive material, an RED could be hidden from sight in a public place (e.g., under a subway seat, in a food court, or in a busy hallway), exposing those who sit or pass close by. If the seal around the source were broken and the radioactive contents released from the container, the device could become a radiological dispersal device (RDD), capable of causing radiological contamination (REMM).