Slide Ring 180 Degree Inside Dia 567.26 mm Outside Dia 656.74 mm Number of Rail Holes 8 Mounting Hole Center to Center 612 mm Mounting Hole Size 6.8 mm Thread Size M6 Screw Type Socket Head Cap Screw Temp Range -20 to 60 Rail Material Steel Rail Finish Precision Ground For Use With FCP44612 Carriage Plate