Box 100 5.0mm x 100mm SPAX Woodscrews with Yellox Coating. The advantages and properties of the internationally exclusive SPAX YELLOX surface include corrosion protection that is more than 6 times greater than that offered by blue zinc plating at the same surface thickness. YELLOX is free of chrome (VI) and thus far more environmentally-friendly than conventional surfaces, both during manufacturing and usage. With YELLOX, the screw retains its yellow appearance with the benefit of higher corrosion protection. These Pozidriv drive recess countersunk flat head wood screws are constructed from a durable hard synthetic coating, 100mm in length and come partially threaded on longer screws. They have ground serrations at the beginning of the thread and are ideal for a range of DIY applications.