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. Size: M3x30mm/35mm/40mm/45mm/50mm Metric screws,total 5 size,different size can meet your different needs. Widely used in most kind of precisions machinerys industry,instrument,electronic product,print projects,household appliances,communication product,lamp,light,toy,. Tips: Product contain small part,keep away from and inadvertent swallow.