These Forgefix Pozidriv Machine Screws are designed for use with nuts or pre-tapped holes. They are Zinc plated for increased corrosion resistance. Their Pan Head with a flat under head surface makes the screws ideal to lay flat on sheet material of all types, thus reducing deformation. APPLICATION: Ideal for use in many DIY, ironmongery, electrical and plumbing applications. 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 substrate’s 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. The Pozidriv screw is similar in appearance to the classic Phillips cross-head.