These Forgefix single-threaded (ST) decking screws have Pozidriv heads and are specially designed, hardened and green treated. The design of the screw helps prevent splitting of the boards, and allowing them to expand and contract with the changing seasons. APPLICATIONSpecifically used in decking applications but also widely used in exterior timber and fencing applications. The 1,000 hour green treated finish offers excellent corrosion resistance to ACQ (Alkaline Copper Quaternary) treated timber used in construction and decking applications. 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 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. Single-thread screws have been designed to offer higher pull out values and quicker insertion.Decking Screw Pozi ST Green Anti-Corrosion Treated 4.5 x 55mm Box 1000