Carbon steel material provides high strength and good durability, available in harsh environment. Precision threads can easily go through various material like plastic, wood, soft metal and more. High in hardness, not easy to deform. There are 450 pieces of screws in 9 size to meet your different needs, suitable for long term use. All screws are sorted by their size and packed in a plastic storage case, convenient to carry and use. Features: 1. Carbon steel material provides high strength and good durability, available in harsh environment. 2. Precision threads can easily go through various material like plastic, wood, soft metal and more. 3. High in hardness, not easy to deform. 4. There are 450 pieces of screws in 9 size to meet your different needs, suitable for long term use. 5. All screws are sorted by their size and packed in a plastic storage case, convenient to carry and use.