-Helical tip from the end of the thread, allowing a better displacement in the wood during screwing and increasing the final adhesion. -Threading thread 40º and optimized pitch for a smooth but fast penetration. -25º tip, which allows easy centring and drilling even in harder woods.
metric sizes: DIN 3124/ISO 2725-1, E DIN EN 3709, ASME B 107.5 M, American sizes: ASME B 107.1, Fed. Spec. GGG-W-641, SAE AS 954-E (test loads), HPQ® high performance steel, chrome plated.