Machine screw is metric threaded fastener, designed to mate with pre-tapped internal thread or nut. It cannot cut thread by itself. Available in various head styles: countersunk, pan head, cheese head, slotted, cross recess etc. Material: carbon steel or stainless steel A2/A4. Surface: zinc plated, black oxide, passivation. Sizes M2~M8. Widely used in electrical cabinet, instrument, appliance and machinery assembly.