ForgeFix Drywall Screw Wafer Head Self Drill TFT ZP - ForgeFix DWSWH13, 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 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 aluminium 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 co