1. [Sizes]M2 x 8mm/12mm/16mm/20mm, M2.5 x 8mm/12mm/16mm/20 mm, M3 x 8mm/12mm/16mm/20 mm, M4 x 8mm/12mm/16mm/20mm button head socket cap screws with matching hex nuts and flat washers, different sizes can meet your different needs. 2. [Material]304 Stainless Steel, stainless steel material which has good corrosion resistance in bad environment like high temperature, cold weather, and high humidity areas. It has superior rust resistance and excellent oxidation resistance, which can ensure long time using. 3. [Package]1280 pieces in total, packed in a durable transparent box with label. It is easy to distinguish the size of the product, when you want to use a certain screw, you can choose the suitable one to meet all your needs. 4. [Wide Applications]Widely used in all kinds of precision machinery industry, classified instruments, instruments, electronic products, printed projects, household appliances, communication products, locks, lamps, lights, toys, etc.