A pack of 50 high-quality machine screws that are made from steel material and have a smooth and durable surface. They have a pan head, which is a flat-topped cylindrical head with rounded edges and a slightly raised top. They have a Phillips cross recess, which is a four-pointed star-shaped indentation that allows for easy driving with a Phillips screwdriver. They have a diameter of 4mm and a length of 20mm, which are measured from the top of the head to the end of the shank. They have a fully threaded shank, which means that the threads run along the entire length of the shank. They have a metric thread pitch of 0.45mm, which is the distance between two adjacent threads. They are used for fastening metal parts together, such as in machinery, electronics, and appliances. They are compatible with M4 nuts and washers, which are available separately
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