20PCS M4.2 Flat Head Self Tapping Screws Drilling Tail Screw Self-Drilling

20PCS M4.2 Cross Recessed Countersunk Flat Head Self Tapping Screws Drilling Tail Screw Self-Drilling Tapping Carbon Steel. Size: M4.2. When tapping into the substrate, keep the axis of the screwdriver in line with the axis of the screw and perpendicular to the plane where the substrate is being driven.