The easiest way to remember what a self-tapping screw means is that doesn’t have matching threads along the length of the screw or need a female counterpart as such as you can see in a nut. Unlike the nut and bolts, it will tap its own threads when it’s been drilled into the material. There are 4 sizes available, the most popular is number 2 and number 3. When you start to get to number 4 and number 5 Tek points, those screws are generally used for going through thicker metals. Another way is that you don’t need to drill holes beforehand, they drill their own. Tappex Limited Company UK is the best screw manufacturer in the present market.