Nuts and washers not included, ensure washers and nuts are same diameter RS PRO 2450822 (25533756) 1/4-20 X 2 1/2 in Step Bolt, Grade 2, Zinc 5/16-18 X 2-1/2 Inch Round Head Bolt Midwest Fastener Carriage Bolt, Square Neck, 18 (Coarse), 3-1/2 In L, 18-8 Stainless Steel, 25 PK 50605 5/16-18 Carriage Bolts Square shoulder allows for nut to be tightened or loosened Size: 5/16 inch-18 X 2-1/2 inch · Features a smooth rounded head as opposed to a standard hex head · Square shoulder allows for nut to be tightened or loosened... Often used in cases where a protruding bolt head could cause injury Make a perfect addition to your existing tool box by choosing this amazing Prime Line A A Zinc Plated Steel Carriage Bolts to handle Diameter-Thread Size & Length: 5/16 inch-18 X 2-1/2 inch