Crafted from 304 stainless Steels,highly hardness,not deformation,antioxidation,wear resistance,resistance,which can long terms use. 200pieces in total,packed in box with labels.It is easy to distinguish the size of the product. Widely used in most kind of precisions machinerys industry,instrument,electronic product,print projects,household appliances,communication product,lamp,light,toy,. Size: M3x30mm/35mm/40mm/45mm/50mm Metric screws,total 5 size,different size can meet your different needs. Tips: Product contain small part,keep away from and inadvertent swallow.