Made of high quality 304 stainless steel, which provides screws and nuts with corrosion resistance,toughness,super hardness, resistance to abrasion and temperature drops. It can be widely used in all kinds of precision machinery instruments,electrical and electronic products,household appliances,communication products and other appliances. M3 M4 M5 Hex Socket Head Cap Bolts Screws Nuts Washers,according with standardized metric system,and the average error is less than 0.01mm. The set is perfect to replace broken and missing screws,the kit has lots of different sizes,which can meet the maximum of requirement for you. You will receive 500pcs machine screws and nuts kit,all come in a box and can be taken out to use when needed to prevent loss. Specifications: Material: 304 Stainless Steel Color: Steel Sizes:M3 M4 M5 Quantity:500pcs Package include: M3*8:30pcs M3*12:30pcs M3*16:30pcs M3*20:30pcs M3 Nuts:120pcs M4*8:20pcs M4*12:20pcs M4*16:20pcs M4*20:20pcs M4 Nuts:80pcs M5*8:15pcs M5*12:15pcs M5*16:10pcs M5*20:10pcs M5 Nuts:50pcs