The Forgefix Phillips fine thread, wafer head Drywall Screws are zinc plated for increased durability. They come complete with a Phillips No.2 insert bit. The screws have a self drilling hardened point designed for fitting dry linings to steel framework without drilling pilot holes. 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&rsquos 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. Zinc plating is the most common, economy, electroplated coating which is normally applied to ferrous components to give enhanced corrosion protection. The relatively low cost, protective nature and attractive appearance of zinc make it a popular coating for nuts, bolts, washers, screws, and similar interior components. In addition, zinc serves as an effective undercoat for paints when high corrosion performance is required. The Phillips screw has four simple tapered slots. It is designed so that a Phillips tip screwdriver can turn a Phillips screw with increasing torque. When the torque gets to be too strong for the tip then the screwdriver tip winds itself out of the screw thus preventing over-tightening and or damage to the screw head. The wafer head distributes the load under the screw head, offering a firm positive fixing in a similar way to that of a washer. Fine thread screws have an extremely sharp point which not only pierces the plasterboard skin but will also allow the screw to drill through thin steel base structures.