Spectre by Forgefix incorporates a long list of advanced screw features, often only found in premium screws, into what we've named advanced multi-purpose wood screw! They feature a countersunk, pozidrive compatible, recessed head - fully threaded, up to 50mm with a sawtooth thread, to prevent splitting and reamer to prevent jacking (50mm and above). They are also surface hardened with a quick start type 17 slash point. The screws have a zinc yellow passivated finish for excellent resistance to corrosion. Zinc yellow passivation process of electroplating is similar to the 'galvanised' and 'zinc plated' processes, with the addition of a yellow dye. It offers an aesthetically pleasing finish. CE approved for use in load-bearing timber construction.