These Forgefix Carriage Bolts are Zinc Plated and ideal for timber to timber joining. They come complete with a hex nut and are fully threaded to 100mm. Also known as 'Cup Square Hex Bolts', the square underneath the Cup stops rotation of the bolt when tightening. They conform to DIN 603 and DIN 934 standards and are available in a comprehensive range of sizes to suit most applications. Primarily used for fastening timber to timber, they are extensively used for timber joist construction in house building and numerous decking applications. A Carriage Bolt, also known as a Coach Bolt or as a ‘Fully Threaded Cup Square Hex Bolt’, has a domed or countersunk head, and the shank is topped by a short square section under the head. The square section grips into the part being fixed (typically wood), preventing the bolt from turning when the nut is tightened. A rib neck Carriage Bolt has several longitudinal ribs instead of the square section, to grip into a metal part being fixed. Zinc coatings prevent oxidation of the protected metal to create a longer lasting finish by forming a barrier and acting as a sacrificial anode if this barrier is damaged. The resulting zinc oxide forms a protective layer against further oxidation.