8 mm, Hex Width 13 mm, Seal Material EPDM, Seal Material - Maximum Temperature 120 Degrees C, Seal Material - Minimum Temperature -40 Degrees C, Average Surface Roughness (Ra) less than 0.5 mm, Nut Material Grade 316L, Standards EHEDG Certified, FDA Compliant, RoHS, For Environment Hygienic, System of Measurement Metric, Nut Material Stainless Steel, Thread Size M8, Thread Depth 9.5 mm, Collar Diameter 18 mm, Washer Outside Diameter 18.8 micron.