The Hillman Group 812621 1/2X4-1/2 Carriage Bolt Product Description Carriage Bolts have a smooth, rounded head that has a small square section underneath. They are used in wood connections utilizing the square neck under the round head which will sit into the hole to prevent the head from turning. These carriage bolts come plated in zinc for moderate corrosion resistance. From the Manufacturer Carriage Bolts have a smooth, rounded head that has a small square section underneath. They are used in wood connections utilizing the square neck under the round head which will sit into the hole to prevent the head from turning. These carriage bolts come plated in zinc for moderate corrosion resistance. Features Carriage Bolts Have A Smooth, Rounded Head That Has A Small Square Section Underneath, They Are Used In Wood Connections Utilizing The Square Neck Under The Round Head Which Will Sit Into The Hole To Prevent The Head From Turning, These Carriage Bolts Come Plated In Zinc For Moderate Corrosion Resistance The Flat-Styled Head Allows For A Smooth Exterior Finish Hot Dipped Galvanized From The Brand: The Hillman Group USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.