M12x120 Cup Square Hex Coach Bolts Zinc Plated

• These coach bolts are zinc plated, and ideal for timber to timber joining.
• They come complete with with a hex nut and are fully threaded to 100mm (unless stated in title).
• Also known as 'cup square hex bolts', the square underneath the cup stops rotation of the bolt when tightening.
• Conforms to DIN603 and DIN934 standards.
• Available in a comprehensive range of sizes to suit most applications.

APPLICATION
Used mainly for fastening timber to timber and is extensively used for timber joist construction in house building and numerous decking applications.

A carriage bolt, also known s a coach bolt or as a 'cup square hex bolt', has a domed 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. It does this by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not trigger a breakdown of the substrates surface integrity as it is formed. The zinc oxide, if left intact, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers.