Slide Ring Full Ring Inside Dia 133.26 mm Outside Dia 184.74 mm Number of Rail Holes 8 Mounting Hole Center to Center 159 mm Mounting Hole Size 5.5 mm Thread Size M5 Screw Type Socket Head Cap Screw Temp Range -20 to 60 Rail Material Steel Rail Finish Precision Ground For Use With FCP25159 Carriage Plate