More informationBICROMATED finish (more resistant to oxidation than plain zinc plating) Flat head- PoziSquare (PSD) with ACR Anti-Camout Recess (Non-slip seat) Reinforced double angle head Robust body Waxed thread as optimal angles Slotted body Quick start screw tip PSD tip included free in each box Also suitable for use with PH, PZ and Robertson