Spax-S Flat C/Sunk Pozi Z/Y Screws 4.5 X 50mm (Box Of 200)

The cross recess Z is a further development of the cross drive by the Phillips Screw Company. The difference is that the four flanks of the screwdriver blade do not taper towards the tip. This increases the lateral hold for the screwdriver bit and reduces the cam-out effect. Typical tapering on conventional cross recess drives causes this to happen, since the cordless screwdriver torque pushes the screwdriver bit upwards.

The countersunk head (also known as the flat countersunk head) has a polygonal underside ("pockets") that mills its way into the wood and can therefore be countersunk without having to pre-drill the screw hole. The flat countersunk head sits flush with the surface.
The screws with partial thread are ideal for fastening thin components like engineered wood boards, panels and floorboards to thicker components like squared timbers or beams. The short thread penetrates the thick component, whilst the thread-free shank remains in the attachment. This creates maximum contact pressure between the two. The thread-free part should be at least the same thickness as the attachment.

The term 4CUT stands for the arrow-shaped design of the screw tip. These edges displace the wood fibres upon insertion and create space for the core diameter of the screw. The expansion at the core of the wood is reduced, preventing wood splitting around the edges. The required cordless screwdriver torque is also reduced, since the screw core no longer needs to "squeeze" into the wood.

Unlike the conventional galvanised screws, YELLOX ist chromium(VI)-free and is therefore much better for humankind and nature alike. YELLOX screws are more resistant to corrosion with the same surface thickness. Despite this, their use is limited to indoor areas. As the name suggests, YELLOX-coated screws have a yellowish appearance.