As in A2 above, the numbers 18/10 refer to the chromium and nickel content- 18% chromium and 10% nickel. The extra cost can be justified, however, because hardware made of A4 stainless steel is extra resistant to tarnish and corrosion, enabling it to last a very long time. The chemical composition of both A2 and A4 stainless steel are almost identical with the most notable differences being the higher nickel content and the addition of Molybdenum in A4.

ScrewCaps UK

For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. This section of our guides and tips hub contains a library of helpful articles such as guides to using screws, screw specification sheets and product reviews on different types of screws such as woodscrews, self tapping screws and decking screws. Molybdenum is a silvery white metal that is highly corrosion resistant, very ductile and has an extremely high melting point. Our selection of A2 fasteners is used for inland rainwater and fresh water to guide against these environments. A4 stainless is often used in marine or chemical environments as it has greater corrosion resistance than A2.If you can't find the information you are looking for here, please don't hesitate to get in contact with us!