110.9 grade alloy steel material has good strength of extension and corrosion resistance in many environments 2Countersunk head enables driving where it doesn't have sufficient space for wrenches 3Ideal for use in confined areas where the head needs to be flush or below the surface 4Used for fasteners in home and office appliance, communication equipment, ship assembly or other machinery industry 5Screws with 8 common thread lengths are well packed in 8 compartments and assorted in a transparent plastic box for convenient use and storage