1They are made of stainless steel and have excellent rust and oxidation resistance to keep long-term use. 2M3 4 5 6 8 hex socket set screw can meet your different needs. 3Set screw assortment kit includes some common sizes so you can easily replace a lost or broken set screw. 4Screws of different sizes are installed in small grids separately for you to choose and use. 5Used for machinery ,industrial fasteners,home improvement,industrial, sports and outdoors.