... .9,4.2,4.8mm countersunk phillips self drilling screws (factory)**key words: self tapping self drilling screws, drilling screws**Material: carbon ... metal, drill holes in advance then locking.**Besides: we also manufacture drywall screws, chipboard screws, self tapping screws, roofing nails, common wire ... wire and so on. please refer to other types of self dirlling screw as below: countersunk phillips ...