Flexible Customized Assortment, More Practical and Cost-Effective, Save Your Time: Comprehensive and well organized. A much more practical and cost-effective way to purchase hardware than individually. You would have no worry to spend a lot of time in finding the correct screws, as the Casaon customized assortment would meet all your demands. There are 570 pcs different types of screws. It includes 285pcs flat head and 285pcs round head, both of them contains M3/M4/M5/M6 specifications and different lengths. So, when you want to use a certain screw, you don't have to waste time buying it separately, because they are at your hand.Rust and Corrosion Resistant 304 Stainless Steel: With the high performance of rust and corrosion resistance, the screws are able to work with no worry in hard environment, such as the wet, acidity, alkaline place of indoor or outdoor.Sharp and Sturdy Phillips Drive Head:It is made from high quality stainless steel and adopt high-precise cutting technology to achieve sharp and sturdy feature, and won't easily strip with the screw gun.Precise, Clean, Sharp Screw Thread:Adopting CNC cutting technology, the screw thread is very precise, clean, sharp, the deep and clear thread can easily penetrate the wood and plastic. Nice Variety of Sizes and Organized in Its Own Storage Bin:Come with a sturdy convenient case and everything is labeled on the case for easily finding the size you need:285pcs Flat head self tapping screws:55Pcs M3x20mm50Pcs M4x12mm40Pcs M4x20mm40Pcs M4x25mm30Pcs M4x40mm30Pcs M5x20mm20Pcs M5x25mm20Pcs M5x40mm285pcs Round head self tapping screws:65Pcs M3x20mm50Pcs M3x25mm40Pcs M4x20mm40Pcs M4x25mm30Pcs M4x40mm30Pcs M5x25mm20Pcs M5x40mm10Pcs M6x50mmWide Application: Casaon self-tapping screws assortment are mainly used in metal, wood, or plastic.