Baypole Self-Drill Screw Phillips Wafer Head ZP 4.8 x 100mm Box 100 - ForgeFix 100BPS4850ZP, These ForgeFix Phillips Baypole Screws with wafer head are specifically designed for joining PVCu sections, particularly in bay windows. The nails have a self-drill tip and are zinc plated for increased corrosion resistance and durability. The wafer head distributes the load under the screw head, offering a firm positive fixing in a similar way to that of a washer. APPLICATION:The large wafer head distributes the load on numerous types of PVCu sections requiring joining. Zinc coatings prevent oxidation of the protected metal to create a longer lasting finish. It does this by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not trigger a breakdown of the substrates surface integrity as it is formed. The zinc oxide, if left intact, can act as a barrier to further oxidation, in a way similar