Set of M4 Socket Head Cap (Allen) Bolt. is ideal for applications that require a well-tooled appearance or broader bearing surface. This screw carries a recessed internal socket drive to add strength. They have a hex drive and flat point with machine screw threads. Its hexagon angular groove depth of more deep, will not slip and vertical shape protruding groove design, hand tightens more convenient. These are the standard, most commonly used hexagon nuts with Metric coarse threads made of heat-treated alloy steel. These high tensile bolt are designed for use in machinery, automotive, electronic components, and heavy equipment. Socket drive prevents slippage when installing into the pre-drilled hole. It is made up of Mild steel (MS) material which offers high tensile strength and excellent corrosion protection. Mild steel (MS) has a higher Mild content, with a matte finish it gives the steel a lower melting point, more malleability and durability, and better heat distribution. An alternative for using them without nuts is to install them directly into a compatible female threaded hole. Hardness is 2 times higher than copper 10 times higher than aluminum. Hexagon angular groove depth of more deep, will not slip and hence more convenient for hand tightening.