Slide Ring 180 Degree Inside Dia 80.63 mm Outside Dia 105.37 mm Number of Rail Holes 4 Mounting Hole Center to Center 93 mm Mounting Hole Size 3.7 mm Thread Size M3 Screw Type Socket Head Cap Screw Temp Range -20 to 60 Rail Material Steel Rail Finish Precision Ground For Use With FCP1293 Carriage Plate