Through Bore Slip Rings may be a Drum or Pancake type assembly. The main feature is the clear inner diameter through the center of the assembly allowing for the passage of fiber optics, air, fluid lines, optical paths or any other device that is required in the structure. The bore size varies from very small for the passage of a single fiber optic cable to several feet in diameter to allow the passage of a person through a CT scanner. Platter style slip rings have been manufactured up to eight feet in diameter to fit the perimeter of the turret in a military vehicle.