Metrick Inverted Internal Ring System of Measurement Metric Location Style Internal Thickness 1 mm Fits Shaft Diameter Not Applicable For Bore Diameter 17 mm Fits Groove Diameter 17.8 mm Fits Groove Width 1.1 mm Fits Groove Depth 0.4 mm Free Inside Diameter Not Applicable Free Outside Diameter 18.3 mm Clearance Diameter Not Applicable Material Spring Steel Material Grade/Class 1060-1090 Tensile Strength Not Applicable Ring Type Inverted Internal Ring