Tite-Fix Exterior-Tite screws Net-Coat Corrosion Resistance coating, ugly rust stains become a thing of the past. The coating is black to match traditional outdoor ironmongery. These screws are case hardened for the perfect balance between core ductility and surface toughness. Exterior-Tite screws have a unique, patented Tri-Lock™ and TS Thread form which joins together the benefits of a single and twin thread in one screw, ensuring a fast and secure fix.The full thread ensures whatever you are fixing stays fixed. Exterior-Tite screws have a Pozidriv Pz2 recess.