Heavy Duty O.R. Rail Clamp. The Mediflex® Heavy Duty O.R. Rail Clamp has been designed to be easy to position on any standard OR Table. It can be applied over 1 or 2 layers of drapes and can be used sterile or non-sterile. While designed specially for Mediflex Table Mounted Products (Long Reach Universal FlexArm™ Holder and Positioners, all StrongArm Holders and Positioners and The Mediflex Draughn Lap-Rack Instrument Holder), it will accommodate most round bar posts ranging from ½” (1.27cm) to 5/8″ (1.59cm) in diameter.