5/16"-18 x 1-3/4" Zinc Finish ASTM A307 Grade A Round Head Carriage Bolt / THREAD CLASS: 2A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 0.875 INCHES MINIMUM FASTENER LENGTH: 1.719 INCHES MINIMUM AND 1.781 INCHES MAXIMUM HEAD STYLE: C30 BUTTON HEAD DIAMETER: 0.688 INCHES MINIMUM AND 0.719 INCHES MAXIMUM HEAD HEIGHT: 0.156 INCHES MINIMUM AND 0.176 INCHES MAXIMUM NECK LENGTH: 0.156 INCHES MINIMUM AND 0.187 INCHES MAXIMUM NOMINAL THREAD DIAMETER: 0.312 INCHES THREAD QUANTITY PER INCH: 18 MINIMUM TENSILE STRENGTH: 55000 POUNDS PER SQUARE INCH NECK WIDTH: 0.307 INCHES MINIMUM AND 0.324 INCHES MAXIMUM MATERIAL: STEEL OVERALL MATERIAL DOCUMENT AND CLASSIFICATION: SAE GR 1 ASSN STD SINGLE MATERIAL RESPONSE OVERALL SURFACE TREATMENT: ZINC OVERALL SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: ASTM B633 ASSN STD SINGLE TREATMENT RESPONSE OVERALL THREAD SERIES DESIGNATOR: UNC