Abstract: The present invention is disclose a metal screw for attaching two thin panels together, such as an anti-loose fastener for joining metal panels. It comprises plurality of relatively small integral tapered angle blocks on underside of the head of the fastener spaced from one another by substantially planar uninterrupted portions of said head and projecting axially therefrom for engaging workpiece. And, the tapered angle block can generate counter stresses which can absorb any ways of torque; namely, be suitable for working in direction instability high frequency vibration environment, and won't loose.