Sizes: M2 x 8/12/16/20 mm, M2.5 x 8/12/16/20 mm, M3 x 8/12/16/20 mm, M4 x 8/12/16/20 mm button head socket cap screws with matching hex nuts and flat washers. Different sizes meet your varied needs. Material: 304 stainless steel with good corrosion resistance in harsh environments such as high temperature, cold weather, and high humidity. Superior rust resistance and oxidation resistance provide long service life. Package: 1280 pieces in total, packed in a durable transparent box with a label. Easy to distinguish the sizes, so you can select the suitable screw without buying separately. Wide applications: Widely used in precision machinery industry, classified instruments, instruments, electronic products, printed projects, household appliances, communication products, locks, lamps, lights, toys, etc. Use scenarios: - Use in assembling precision machinery projects or CNC setups where multiple sizes are required. - Replacing fasteners in electronic product housings or instrument panels to improve reliability. - Mounting lamps, lighting fixtures, or household appliances that require sturdy stainless steel fasteners.