Goldscrew Yellow zinc-plated Carbon Steel Woodscrews (Dia)4mm (L)20mm Pack of 200. This pack of Prodrive drive recess double countersunk head wood screws are constructed from a durable double hardened core are 20mm in length & come fully threaded. They have a rifled shank with deep thread & come wax coated for lubrication. They're ideal for a range of DIY applications.