The Special Drill Point (Sd) , can drill the thickness 3.2mm. steel purlin and can screw directly without pre-drill.
Made from the high quality steel (c-1022) through the yellow passivated process for the effective protection from the stain and hydrochloric acid.
extra width screw head to prevent the leakage and for more effective tight grip on the roof , the real epdm rubber washers for more effective leakage proof.
in addition we also have the color head screws to match with the roof color , make the perfect roofing.