These Forgefix Multi-Purpose Pozi Compatible Screws with countersunk heads have a zinc finish for increased durability. The screws are immensely popular and versatile, and used in all trades including joinery, electrical and plumbing. Also widely used in DIY applications. APPLICATIONSuitable for use with many materials including PVCu, Timber, Chipboard, MDF, and other similar types. 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. The Pozidriv screw is similar in appearance to the classic Phillips cross-head, but in fact is ver