304 high quality stainless steel. Stainless steel is a common material with a density of 7.93 g/cm3, also called 18/8. It has good workability and high toughness up to a a temperature of about 800 degrees. Various screw sizes:M38,M312,M316,M320,M48,M412,M416,M420,M58,M512, M516,M520,M68,M612,M616,M620, to meet different needs. It is a very essential hand tool for the family. With M3, M4, M5 and M6 nuts and washers, installations are now more precise with an increase in contact surface, which reduces pressure and protects parts and screws. > Nuts and washers are arranged in a storage box, making it easy to find the series and avoid loss when needed. They are anti-oxidizable and corrosive even at high temperatures. The main use of stainless steel hex screw is very common in electronics, electrical appliances, chemicals, water, machinery and equipment, furniture and many other fields. Screw Dimension: M38 /12/16 /20mm–10 Pieces each M48 /12 /16 /20mm–10 Pieces each