These Forgefix single thread Coach Screws are Zinc plated for increased corrosion resistance. Their hex head enables higher torque capability when tightening, and increased speed of use with socket drivers.These Coach Screws conform to DIN 571 standards. APPLICATION:Used widely in heavier timber installations and for fixing timber to masonry. Also popular as a fixing for satellite dish installation together with a rimmed or rimless wall plug. 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. Single thread screws have been designed to offer higher pull out values and quicker insertion.