Open Stereotactic System (OSS) is designed to be used in CT and MRI scanners. The small diameter of the head ring makes the system suitable for even the smallest of the MRI head coils. The open head ring is made of high-tech ceramics that offers excellent mechanical stability and artifact rejection in general. Using interface components, like the closing segment, the system comes with the available adaptations compatible with all the traditional stereotactic products such as the ZD and RM aiming devices. The open design gives the patient more freedom in the facial area and allows the surgeon to plan approaches that are not possible with a conventional closed ring. Moreover, a special CT and MRI compatible localizer provides simplicity.