These Forgefix Multi-Purpose Pozi Compatible Screws with countersunk heads have a zinc yellow passivated 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. APPLICATION Suitable for use with many materials including PVCu, Timber, Chipboard, MDF, and other similar types. The Zinc Yellow Passivation process of electroplating is similar to the 'Galvanised' and 'Zinc Plated' processes but with the addition of a yellow dye. It offers an aesthetically pleasing finish, whilst having excellent resistance to corrosion. The Pozidriv screw is similar in appearance to the classic Phillips cross-head, but in fact is very different. The Pozidriv has four additional points of contact, and does not have the rounded corners that the Phillips screw drive has. The biggest advantage it offers is that, when used with the correct tooling in good condition, it does not cam out, allowing great torque to be applied. The Pozidriv screw can easily be distinguished by a line embossed in the screw head at 45° to the slots for the driver. The countersunk head is designed to sink flush with substrates to leave a smooth surface finish. They have single threads, designed to offer higher pull out values and quicker insertion.