Spacer Spacer Type Round For Screw Size M4 Overall Length 4 mm Inside Diameter 4.2 mm Outside Diameter 8 mm Retaining Rib Diameter Not Applicable Material Aluminum Finish Plain Pack Size Small Pack System of Measurement Metric Hex Width Not Applicable Color Silver Hex Width Tolerance Not Applicable Inside Diameter Tolerance +/-0.13 mm Outside Diameter Tolerance +/-0.13 mm Overall Length Tolerance +/-0.13 mm Rockwell Hardness B50 Tensile Strength 45 000 psi