Flat head sheet metal screw has a flat top that tapers down to a cone shape at an 82 degree and will sit flush into a countersunk hole giving a finished appearance. They are ideal use for wood, metal or other tough materials and known for their effecient application performance and endurance. You could see them around because they are widely used in a variety of industries such as construction, manufacturing, engineering, assembling and so on. The high quality 304 stainless steel provide perfect strength and good corrosion resistance in bad environments like high temperature, cold weather and high humidity areas without the need for time consuming and costly maintenance. Contact Us: If you have any questions when using, please feel free to contact us by Amazon message.